About filtration

[Boris]

I am new here and going through older posts and found one that I would like to revisit. My health is a bit periodic. Some months I can spend a lot of energy on the fish and some I can only do the necessary maintenance. Consequently I need to adapt my setup for those low points. Filtration and water quality is something that I am not quite comfortable with and am seeking to optimize for me. Currently I have used a canister filter mainly as a mechanical filter without biological media. It works great but fills up and clogs rather quick. I have a lightly stocked tank and use the tank and scape as biological filtration but now I want to get a group of synodontis which will multiply the load so I need a new strategy.
I found this post viewtopic.php?p=302319#p302319 from 2016 but fortunately the OP is still on the forum.

I have this idea, and please correct me if I am wrong, that if I have good mechanical filtration and clean it every week I will remove a significant amount of waste before it is broken down into nitrates. Thus the water quality keeps longer. A common opinion on under gravel filters is that it moves the detritus out of sight but not out of the tank. This is true but so do canisters or sponge filters unless they are cleaned.

The matten filter approach is interesting but how good is it on mechanical filtration? The water flow into the intake of a canister filter is quite high and any debris passing close enough will be sucked in but if the intake is behind a matten filter the water flow through the mat will be quite low?

So is it better to remove waste often or can it be left in the water for longer periods? I would like to hear your thoughts about this?

[Bas Pels]

As you stated, there are periods when tank maintenance is work for you. That implies you want to cut down on this maintenance.

The less fish your tank contains, the less you need to do, and the less impact skipping one in e while will have.

A tank which has 50 % of its water changed, three times a week, with UV light and heavy filtration - such a tank will collapse when a water change is skipped. A tank with few fish, harly any maintenance, will endure.

My best advise would be to look hard on what fish you have, and try to reduce the total.

You clean the canister filter every week, and between the lines I get the feeling it also needs cleaning. To me, this would mean the filter is too small. When I used canister filters I never cleaned it within a month. A fresh one needed cleaning after a month, than 2 months and soon it was on a comfortable 4 month interval.

However, this is not what you asked.

I have all my tanks filtered with matten, or without. A dead leaf might be suck to this filter, but it decayes. And, frankly, I think the phosphates and nitrogen compounds will be among the first to leave, leaving a skelletton of rather harmless compounds (such as cellulose) behind.

This does not answer you query regardingmechenical filtration, at least not for really large debris. It does for small debris, as this is contained in the mattan or between them. After all one can use coarse, middle and fine in a row.

But, my experience is that the really fine matten need to be rinsed regularly, certainly afrey fortnight or so.

As I´m lazy AND have multiple tanks (13, increasing to 18) I rather hqave systems maintaining themselfes.

[dw1305]

Hi all,

.....Currently I have used a canister filter mainly as a mechanical filter without biological media. It works great but fills up and clogs rather quick..........So is it better to remove waste often or can it be left in the water for longer periods? I would like to hear your thoughts about this? I have a few questions

This is honestly a sure recipe for disaster. Have a look at <"Using deep gravel...."> I've linked in page 5., but the whole thread is worth reading.

I have a lightly stocked tank and use the tank and scape as biological filtration

When you say "scape" do you mean the tank is heavily planted? Plants are a very important component of biological filtration and greatly increase the nitrification potential of the tank.

.............I have this idea, and please correct me if I am wrong, that if I have good mechanical filtration and clean it every week I will remove a significant amount of waste before it is broken down into nitrates. Thus the water quality keeps longer.

This bit is really important, you need the filtration system to remove the ammonia (NH3/NH4+) and subsequent nitrite (NO2-) as rapidly as possible. Both mechanical filtration and nitrate levels aren't that important in terms of water quality.

You can't see the ammonia that continually diffuses from your fishes gills, or the nitrite that succeeds it, but they are the killers. Nitrification, the conversion of ammonia to nitrate is an oxygen intensive process, so as well as micro-organisms and plants you need plenty of oxygen.

If you use your canister filter as a syphon, you won't have effective nitrification (because of the lack of oxygen) and ammonia levels will rise, killing all your fish.

.......... A common opinion on under gravel filters is that it moves the detritus out of sight but not out of the tank. This is true but so do canisters or sponge filters unless they are cleaned.

The matten filter approach is interesting but how good is it on mechanical filtration? The water flow into the intake of a canister filter is quite high and any debris passing close enough will be sucked in but if the intake is behind a matten filter the water flow through the mat will be quite low?

Matten filters are very good for biological filtration, mechanical filtration is really more a matter of aesthetics. Have a look at Stephan Tanner's web site..

cheers Darrel

[Boris]

Thanks for the replies!
I will read through the links.
I am sorry that I was unclear so just to clarify, I measure nitrates and do weekly water changes, empty "gunk" from canister and replace filter floss in top basket. Tank is 100 gallons. The surface area of the tank, rocks, bog wood and plants plus one basket of bio rings in the canister filter seem adequate for nitrification for 50 small tetras, ten panda corys, three ancistrus with fry and some shrimp (I also have Pothos but it doesn't do much during winter due to lack of light). I have had live bearers but I removed them because of all the fry that survive and have to be given away. Fry and shrimp indicate ok water?

I aim to replace most (all?) of the fish with a group of S. multi. or S. luci. which is a completely different bio load. Subsequently I will use the canister filled with media and so am looking for method of mechanical filtration as my main idea was "remove waste from water before it decomposes".

[Viktor Jarikov]

IMHO you are getting world class advice above.

One needs indeed to pay attention to ammonia and nitrite as these are literally 1000x more toxic to fish than nitrate... and in the case of a normally set up biofilter, all of ammonia that enters it is converted to nitrate inside the filter... and ammonia and nitrite must always read at zero ppm at any time in your fish tank by the recommended tests, which are of the liquid, test tube kind.

Darrell was also the esteemed peer that opened my eyes to the importance of DO, the crucial factor overlooked, it appears, by most fish keepers. Many, like I used to be, aim to increase the size or capacity of their biofilter while in many cases it would be easier, cheaper, and more effective to increase the aeration of the water going into the biofilter... and in many cases increasing the size of the biofilter or the amount of media in it might not result in any improvement at all if the beneficial bacteria are already starved of oxygen as it is...

The later stages of the waste decomposition you are speaking of only take up DO from your water and their final products of decomposition are CO2 and H2O and they do not produce ammonia or nitrite, so these processes, while requiring valid attention, do not share the acute intoxication problems caused by ammonia and nitrite.

In sum, you seem to be focused on the valid thing but the one of low priority and you are missing out on the main killer by not measuring, thinking, or paying attention to NH3 and NO2.

[Boris]

IMHO you are getting world class advice above.

The later stages of the waste decomposition you are speaking of only take up DO from your water and their final products of decomposition are CO2 and H2O and they do not produce ammonia or nitrite, so these processes, while requiring valid attention, do not share the acute intoxication problems caused by ammonia and nitrite.

In sum, you seem to be focused on the valid thing but the one of low priority and you are missing out on the main killer by not measuring, thinking, or paying attention to NH3 and NO2.

Yes, that makes sence and i get your points.
I will put media in the canister and increase aeration.

I do test for ammonia and nitrite and the only time it was not zero was when I added fish and increased feeding too rapidly, otherwise I would of course have increased filtration.
My setup is an experiment, and in my view a successful one, along the lines of "How much surface area do you need?" No one seems to know the answer but there will only be as much bacteria as there are compounds for them to feed on no matter how much extra surface area there is?
For a molecule of ammonia to be converted to nitrite and nitrate it must come in contact with the bacteria. If a sponge filter with an air stone is the main filtration then how long does it take for ammonia to get to the filter from the other end of the tank? If the majority of the bacteria are on every surface in the tank, most of the ammonia will be converted on the way to the sponge. This would mean that water flow is more important than more surface area?
In case of a power out, which I have occasionally, the water will not enter a canister filter where the bulk of bacteria are but with the bulk of bacteria in the tank, even without a battery powered air stone the process will keep going?

I have put question marks on my statements because I mean to discuss, or be corrected, and not to argue.

[Viktor Jarikov]

B: I do test for ammonia and nitrite
VJ: good to hear.

B: "How much surface area do you need?" No one seems to know the answer
VJ: I think I have seen general guidelines and this question is amenable to rather simple calculations.

B: but there will only be as much bacteria as there are compounds for them to feed on no matter how much extra surface area there is?
VJ: agreed, DO and food (concentration of oxygen and ammonia and nitrite) would determine the amount of BB's at a given temperature.

B: If a sponge filter with an air stone is the main filtration then how long does it take for ammonia to get to the filter from the other end of the tank?
VJ: This is determined by the turnover rate of filtration and the stirring inside the tank indeed.

B: If the majority of the bacteria are on every surface in the tank,
VJ: majority or not but every surface that is not wiped is indeed covered with the BB's

B: most of the ammonia will be converted on the way to the sponge. This would mean that water flow is more important than more surface area?
VJ: They are both important and it is important to balance both or one might be either underfiltered with too little surface or might be stressing the fish out that can't swim as they'd like in the aquatic hurricane force currents.

B: In case of a power out, which I have occasionally, the water will not enter a canister filter where the bulk of bacteria are but with the bulk of bacteria in the tank, even without a battery powered air stone the process will keep going?
VJ: In this scenario it depends heavily on the bioload. With high bioload, that's a lot of fish, the factor that will kill or sicken your fish first could easily be the DO drop before any problems with the NH3 and NO2 poisoning raise their ugly head. If all your BB's are in the tank and they complete with the fish for DO, your scenario could work against you.

B: I have put question marks on my statements because I mean to discuss, or be corrected, and not to argue.
VJ: thank you. Same here. I am here to learn too.

[Boris]

Great replies, thank you!
While we are on the subject, I have an Eheim canister filter with four different kinds of media with different shapes and pore sizes and an enormous surface area for BB. When wet the capillary forces draws water into the depths of these pores which are then coated with BB. How does ammonia and nitrite move into these pores? I think the capillary forces inhibit any water movement so I can only think of equilibrium driven diffusion which works but is a comparatively slow process. Isn't the actual outside of the balls/cubes/rings the only surfaces actually involved in the nitrification process? If so we would benefit more from K1 media in our filters than these porous media?

[dw1305]

Hi all,
Before I write anything else I should say I'm a pretty shoddy fish-keeper compared to people like Viktor, and it was partially because I needed all the help I could get that I became interested in de-skilling fish keeping.

.....My setup is an experiment, and in my view a successful one, along the lines of "How much surface area do you need?" No one seems to know the answer but there will only be as much bacteria as there are compounds for them to feed on no matter how much extra surface area there is?

That is an interesting question. <"Dissolved oxygen"> is definitely the limiting factor for nitrification, particularly when you deal with more concentrated organic wastes. Have a look at <So what is organic waste?"> thread on UKAPS it talks about Biochemical Oxygen Demand (BOD).

..........For a molecule of ammonia to be converted to nitrite and nitrate it must come in contact with the bacteria. If a sponge filter with an air stone is the main filtration then how long does it take for ammonia to get to the filter from the other end of the tank? If the majority of the bacteria are on every surface in the tank, most of the ammonia will be converted on the way to the sponge. This would mean that water flow is more important than more surface area?

You can use laminar flow to compensate for tank architecture. You can get high flow rates with an air-stone and uplift tubes, have a look at the "jet-lifters" on the <"Swiss Tropicals"> website. People often underestimate the contribution of plants to nitrogen removal, "plant/microbe" biofiltration is very effective and out-performs "microbe only" in nearly all circumstances.

.....In case of a power out, which I have occasionally, the water will not enter a canister filter where the bulk of bacteria are but with the bulk of bacteria in the tank, even without a battery powered air stone the process will keep going?

Yes, you can compensate for "single point of failure" by having multiple sites for nitrification. Multiple sites for nitrification are an unalloyed good thing, you can never have too many. The actual rate of nitrification is going to depend on all sorts of factors but we also now know that nitrification is carried out by a much wider range of organisms than were initially isolated, and that many of them belong to the Archaea and occur in conditions (low ammonia levels, low pH, low O2) where nitrification wasn't thought to occur.

cheers Darrel

[Boris]

Hi Darrel!

<"Dissolved oxygen"> is definitely the limiting factor for nitrification, particularly when you deal with more concentrated organic wastes. Have a look at <So what is organic waste?"> thread on UKAPS it talks about Biochemical Oxygen Demand (BOD).

I agree, DO's importance for the other processes is something I have overlooked.

"Cory" from Aquarium Co-Op did a test measuring DO in different setups.
https://www.youtube.com/watch?v=8ijCUmFM7Ww&t=s
6.1ppm -55g with Surface plants with Sponge filter.
6.9ppm - 55g Without surface Plants with sponge filter.
7.4ppm - 55g With Fluval 406 Canister Filter at Surface and sponge filter.
6.7ppm - 55g Fluval 406 Canister at water surface only.
5.4ppm - 55g Fluval 406 Canister below water surface.
7.4ppm - 55g Aquaclear 110 Hang on Back falling into tank.
6.9ppm - 55g Aquaclear 110 Hang on Back at water surface.

You can use laminar flow to compensate for tank architecture. You can get high flow rates with an air-stone and uplift tubes, have a look at the "jet-lifters" on the <"Swiss Tropicals"> website.

You can but if you look at breeders, fish rooms and aquarium shops the most common is the cylindrical sponge with a 2" flow tube. I realize these tanks are also mostly on auto water change but many smaller tanks have this as the only source for water movement.

The actual rate of nitrification is going to depend on all sorts of factors but we also now know that nitrification is carried out by a much wider range of organisms than were initially isolated, and that many of them belong to the Archaea and occur in conditions (low ammonia levels, low pH, low O2) where nitrification wasn't thought to occur.

Do you have any suggestions for good reading?

[dw1305]

Hi all, hi Boris,

...........I agree, DO's importance for the other processes is something I have overlooked.

"Cory" from Aquarium Co-Op did a test measuring DO in different setups.
https://www.youtube.com/watch?v=8ijCUmFM7Ww&t=s
6.1ppm -55g with Surface plants with Sponge filter.
6.9ppm - 55g Without surface Plants with sponge filter.
7.4ppm - 55g With Fluval 406 Canister Filter at Surface and sponge filter.
6.7ppm - 55g Fluval 406 Canister at water surface only.
5.4ppm - 55g Fluval 406 Canister below water surface.
7.4ppm - 55g Aquaclear 110 Hang on Back falling into tank.
6.9ppm - 55g Aquaclear 110 Hang on Back at water surface....

They look about right. He has obviously thought about oxygenation, and they are all quite good set-ups. Trickle filters are the "Rolls-Royce" of filters. As he suggests the nature of the surface plants (Lemna minor) and the lack of submerged plants will reduce the dissolved oxygen levels in the "55g with surface plants". If the floating plant had been Pistia those values would have been much nearer saturation, because it doesn't forma as flat a carpet and tere are air spaces under the leaves.

.........The actual rate of nitrification is going to depend on all sorts of factors but we also now know that nitrification is carried out by a much wider range of organisms than were initially isolated, and that many of them belong to the Archaea and occur in conditions (low ammonia levels, low pH, low O2) where nitrification wasn't thought to occur.......

Do you have any suggestions for good reading?

I do.

If you have a look through the last three pages of <"Using deep gravel....."> and another UKAPS thread <"Bedside Aquarium"> it will link you into some scientific papers.

I might start with "Bartelme RP, McLellan SL, Newton RJ. (2017) Freshwater Recirculating Aquaculture System Operations Drive Biofilter Bacterial Community Shifts around a Stable Nitrifying Consortium of Ammonia-Oxidizing Archaea and Comammox Nitrospira. Frontiers in Microbiology."

cheers Darrel

[Boris]

As he suggests the nature of the surface plants (Lemna minor) and the lack of submerged plants will reduce the dissolved oxygen levels in the "55g with surface plants". If the floating plant had been Pistia those values would have been much nearer saturation.

What is the difference? I thought that the blocked surface area was the limiting agent?

I have read som of the links provided and your posts are a rabbit hole that keep linking too more and more knowledge!
I'll shut up for a bit and keep reading...

[Bas Pels]

With regard to the measured oxygen levels, even if I assume the tests have executed properly (a dissolved gas measurement is not easy, unless done with an electrode) the question is what has been measured.

If water gets older, less ocygen can dissolve. We don´t know anything about the tanks, and therefore the measurements only tell us how long it has taken from the last waterchange.

Floating waterplants can use carbon dioxid from the air, which enables them to grow much more rapidly, using nitrates from the water, but they don´t grow that well in moving water. And moving water helps to dissolve oxygen.

What you can do, in order to take the best from two worlds, is use a plant like Monstera which has air roots, and these can be put into the tank, withdrawing nitrates without stipping the flow. I have a few tanks with Cyperus growing in the mattenfilter, effecting the same. But this requires space above the tank, and is therefore only possible for an open topped tank.

These options will reduce nitrate levels and thus the need to change water.

[dw1305]

Hi all,

What is the difference? I thought that the blocked surface area was the limiting agent?

It is. The problem with Lemna is that it forms a flat cover, very much like laying a sheet of polythene on the water surface. That is really healthy Lemna in the video (nice and dark green), and Lemna is capable of exponential growth rate in nutrient rich, hard water (like the tank). When he scoops off the Lemna he is exporting a lot of nutrients, if that tank didn't have a floating plant nutrient levels would rapidly rise. You can get a layer several plants thick, and this drastically reduces the gas exchange surface area.

Part of the reason why wet and dry trickle filters are so effective is that they have a huge effective gas exchange surface area caused by the film of water flowing over the filter media. @Bas Pels are good suggestions. Diana Walstad, in the "Ecology of the Planted Aquarium" called this the "aerial advantage".

I have read some of the links provided and your posts are a rabbit hole that keep linking too more and more knowledge!

There is a huge amount of scientific literature out there. You can be a successful aquarium keeper without understanding the processes that occur in the tank, and nothing beats experience, but a little knowledge, and critical thinking, gives you a real advantage, partially because it stops you doing really silly things.

I'll hold my hands up, I've been a truly terrible fish keeper. It wasn't that I didn't care, I cared passionately, but I didn't really know what I was doing, there wasn't the internet (or even really any books) and I kept following advice that led to the frequent periodic demise of the fish.

But the past is a different country, now there is information, the real problem is that there is too much of it, and a lot of it isn't very good.

This forum doesn't have anything to sell you, but it has experts/administrators/owners who really know what they are talking about and don't have any hidden agenda.

cheers Darrel

[Boris]

There is a huge amount of scientific literature out there. You can be a successful aquarium keeper without understanding the processes that occur in the tank, and nothing beats experience, but a little knowledge, and critical thinking, gives you a real advantage, partially because it stops you doing really silly things.

I don't need to understand the processes but I want to!
I have a scientific education, used to have a science based job, but I got ill with ME/CFS. I can no longer work, can no longer read a book, most days I can get through some of the morning paper. Fish tanks is the most scientific thing I can still do and I love to relearn things I should have known, and probably did, but had forgotten.
I was getting complacent and probably doing silly things but you guys woke me up in a good way. Thank you!
I am rearranging my tank to have a less deep sand bed, more filtration, more aeration and a plant spotlight for the Pothos.

I have printed the Bartelme et al.article but it will take a few weeks to get through it. A few commas in the head line would have made it easier to grasp. Just saying...

[dw1305]

Best of luck.

cheers Darrel

[Viktor Jarikov]

Sorry to hear of your trouble. I could spot you are of science.

I too am a scientist turned (well... turning) fish keeper / aquariumist, if there is such a word.

There is so much bad or subpar literature out there, which is what makes recommendations like those of Darrell invaluable because he had already done a lot of critical sifting and offers us a refined and relevant product.

TBH I have been following Darrell's advices for many years but I've not read all his links for other pressing priorities and general laziness. Which is why I like to be presented the gist of the knowledge here on a forum, on a silver platter and to use this I only need to know who I can trust haha...

[Boris]

Darrel is not a PhD?

I was browsing and came across this video by "Joey - King of DIY".
https://www.youtube.com/watch?v=1O3B7BiJkwU

To sum it up: His rule of thumb for sizing a canister filter for your tank - you need to divide the advertised flow rate in half to get actual flow rate (true).
Then decide what turn over you want ex. 3 times/hour.
This gives the volume of the tank that it will adequately filter.

I checked my filter: Flow rate 330 gallons/h so half is 165.
165/3= 55
My tank is 100 gallons so if I was to follow this I actually need another filter of the same size or one with double the flow rate?

What do you think of this?

[dw1305]

Hi all,

Darrel is not a PhD?

I'm not, I started a Ph.D, but for various reasons I never finished it, so I'm a "Master of Philosophy" (University of Bath, 1992).

My project was on using "Spent mushroom compost as a horticultural growing medium", and after a year I told my sponsor ("Blue Prince Mushrooms", owned by Heinz) that it had "no future what so ever", and they told me that I had "no future what so ever" and removed my funding.

I'd like to point out that, 28 years on, I am not bitter at all about this, and that I an fully over it, and that my decision not to eat any of Heinz's products over the last thirty years has nothing to do with this what so ever.

cheers Darrel

[Boris]

I am setting up my Synodontis tank and there will be rock work over more than half of the foot print. As egg crate is not easily found over here I am using this under gravel filter under the rock piles. I am NOT using it as a filter, only for load distribution of the rocks. It is about half an inch high and as you can see less than 50% of the surface is open to circulation or diffusion.
Now, do I fill the gap beneath it with substrate (sand) or do I leave it uncovered?
If I leave it as a void it may collect debris which will be hard to remove.
If I fill it up with sand I may get anaerobic conditions which could be both good or bad?
Opinions please!

[Bas Pels]

Basically, you want this filter to carry your rockwork. That is, rather heavy stones.

If I look at the plastic, I wonder whether I woult trust this to carry say a 5 kg (some 11 pounds) stone.

I myself use styropore plates (sold for insulation) of 2 cm thick for precisely this purpose. I use tiles over them in order to keep them from floating, but these tiles also protect the styropore from any rocks

[Viktor Jarikov]

To me it sounds like you will have problems vacuuming the substrate and getting all the crud out. If you will have a layer of sand, I am not sure why you'd need an additional weight-distributing / safety contraption.

[Boris]

To me it sounds like you will have problems vacuuming the substrate and getting all the crud out. If you will have a layer of sand, I am not sure why you'd need an additional weight-distributing / safety contraption.

As far as I am aware sand is not considered a sufficient support for heavy rocks. The rocks will settle on the glass bottom creating point loads.
Yes, it will be difficult to vacuum under the rock piles in any case?

[Viktor Jarikov]

In my mind I thought the fish are not diggers (perhaps I am wrong) and that you'd be lifting the rocks and vacuuming under them and setting the rocks back on the sand surface.

If you think of a more permanent installation, then perhaps you are right and you could set up tiles under the rocks, with or without the styrofoam mentioned by Bas, but he and other "substraters" should know better... because the last time I used substrate in my tanks was a decade ago... and even then I have never used sand, always fine or medium gravel. I have never bothered with any weight distribution of the heavy furniture.

If I am not mistaken, the bottom glass panes of small to medium (or all?) fish tanks are tempered. They can withstand a LOT of point load. Hit it with a hammer almost as hard as you can, you won't break it or will be surprised at the force you will need to finally break it... or such is my experience anyway.

[Boris]

Somehow I had missed Bas reply.
I don't have access to large rocks so I will stack smaller ones in piles to create hidy holes.I have used styrofoam before but had the problem of it floating.
I'll see what I can find in the way of tiles?

[Kilo_SSK]

Speaking of filtration, if I'm not mistaken, room temperature and sunlight exposure play a role in the speed at which flora develops in a fish tank, and thus, in the quality of filtration needed. The thing is that right now, I've only owned a fish tank in a room that doesn't get much sunlight, but I was planning to move to one of these flats on the Costa Blanca by late 2021/early 2022, and I've never had to care for a fish tank under that climate.
Should I be careful about something in particular, or would it be possible to keep filtrating the water of said tank at the same rate as usual?

[Bas Pels]

if the tank gets too much sun AND there is enough plantfood in the water - this water might get green. Resulting in 0 visibility.

You better keep the sun out of the tank.

Further it is warmer there, but that only implies other species kept.

[Jools]

Leave it, a siphon will be able to remove built-up debris if you wish. If you were going to put something under it, perhaps small rounded stones like you would use in a garden path or driveway?

Jools

[TwoTankAmin]

I am a huge fan of Mattens. I have 3 tanks which rely primarily on them. Almost as much, I like the Poret foam cubes. This is a brand and I am sure there are other brands as good, I just ended up using this one.

The hardest thing I had to learn about using massively pored foam filter media was that it does a better job of mechanical waste processing than floss. I use almost exclusively the 20 ppi foam. 10 ppi is great for intake pre-filters or in canisters with more than two layers/baskets of media. Higher ppis clog pretty fast and are best used in shrimp and fry tanks, imo. I came to the Poret Mattens and cubes because I am noe in my early 70s and the work load of 20-25 tanks had been getting more difficult in the recent years. The Poret made filtration a lot easier to keep clean and maintain without sacrificing water quality which was my goal. At one time I had over 26 running AquaClears, today I have just 14 and I plan to reduce that number in the next few weeks.

While I will not argue that a planted substrate is one of the best "filters" one can have, they are not always possible. Nor will I argue against the importance of adequate oxygenation in promoting a healthy tank. However, I have never seen evidence of an oxygen shortage in any of my tanks including the 12 or so tanks with no plants with some of them also being bare bottom.

Big foam filter media will tend to do a fair amount of denitrification and still not result in water which is short on oxygen. I do not need to do all sorts of complicated testing to know this. I use these filters in tanks where I keep Hypancistrus species breeding and growing out. I have a lot of Xingu river fish and they live in water temps from the low 80s F to bouts of time at 90F+. This water temp tends to hold less oxygen than cooler water. But the fish have a need for high oxygen levels. My plecos do not die very often, do grow nicely and do reproduce successfully, QED the water must be OK in terms of oxygen levels being adequate and nitrogen levels being almost absent (i.e. not testable without expensive lab equipment).

The other thing it took me a while to learn was that filtration and circulation in a tank are not the same thing. For most in the hobby, their filter(s) adequately oxygenate the water. Moreover, as noted above, the bacterial colonies will ultimately size to the available bio-load. Therefore, if there is insufficient media/filtration to handle the nitrogen, the bacteria will colonize in other places. In substrate, under rocks and wood or other decor, they will establish and multiply. And they will colonize in the greatest numbers where the things they need are most available, i.e where flow/circulation delivers them.

Rather than trying to overpower a filter to get the desired level of circulation, it makes much more sense to divide that job between different pieces of equipment. A few small pumps and/or powerheads can insure that the water in a tank gets adequate circulation rater than a single large device which might blow some fish out of the tank.

Things can circulate pretty fast. I have seen this in my 55gal. Altum angel tank which has a digital monitor that continuously reads TDS/Conductivity, Temperature and pH. Between water changes the pH, targeted to be 6.0, tends to creep up towards 6.5 Sometimes mid-week I will add muriatic acid to the tank to drop the pH. I have actually a few times dropped the pH by close to one full point (1.0) and seen this happen on the monitor in about 5 minutes or less. I do dose the acid all across the surface rather than in a single place. (Filtation on this tank is 2 AC 200s, and air driven 4x4 poret 20 ppi and a large ATI sponge.)

Finally, there is one other consideration regarding ammonia and planted v.s. non-planted tanks. The plants take in ammonium (NH4) and the bacteria prefer ammonia (NH3) which is way more toxic. Even in a higher pH tank most of the Total Ammonia (TA), which is NH3 + NH4, is in the form of NH4. However, it is possible to remove virtually 100% of TA if one removes exclusively one or the other form. As soon as one form is removed, the remaining form converts partially and restores the balance for that water's specific parameters.

Plants can consume NH4 way more rapidly than bacteria/archaea can consume NH4. However, aquatic plants are covered in nitrifying bacteria. Moreover, some plants will transport oxygen down and out through their roots to turn an anaerobic space aerobic which encourages the colonization of the nitrifiers. So, no matter how many plants may be in a tank, there will still be some amount of nitrifying bacteria at work. On the other hand, it is possible for a tank with no plants or algae and even no substrate to process ammonia solely by the microorganisms. Nature always finds a way.

All that said. I still have a number of heavily planted tanks that I enjoy. When it comes to fish keeping, there is more than one way to skin a cat (just an expression). My fish have all of their skin/scales/scutes.

[Lycosid]

I am a huge fan of Mattens. I have 3 tanks which rely primarily on them. Almost as much, I like the Poret foam cubes. This is a brand and I am sure there are other brands as good, I just ended up using this one.

I'll second this. I have a whole aquatics lab running off Mattenfilters, and we never have water quality issues.