High Nitrate

[Redtailrob]

Hi all.

Run some water tests on my Big 370G (UK) set up last night, as a few of my Big Cats, Tig in particular has been looking off colour.
pH 7.5 - a little high for my liking
Ammonia 0.1mg/l
Nitrite - No trace.
Nitrate........Now this is the scary one 100mg/l.

Will carry out a big water change tommorow and will also give the sump a much needed clean.
Will also check the Nitrate level of my Tap water!!
Will the addition of a few big Plants help to reduce the Nitrate load??

[MatsP]

High nitrate is generally a sign of the combination of heavy feeding and not enough water changes. Ammonia level of 0.1 is not great (if that's distinguishable from 0.0) - it indicates that you haven't got sufficient filtration. Keep an eye on that one, as it can easily cause problems for sensitive fish - something that main channel catfish are!

Cleaning the sump will probably have little effect unless there are large amounts of something deteriorating (food, plant matter, dead fish, etc). Too much thorough cleaning of the filter system can cause a mini-cycle (nitrite and ammonia levels going up whilst the bacteria culture re-establishes itself).

Nitrate is pretty difficult to get rid of - you CAN have an anaerobic filtration system, but they are not easy to maintain on a medium-sized scale. There are large scale commercial denitrification units in public aquaria, but that is massive scale compared to a home aquarium, even a 300+ gallon system is small in comparison - the filter I heard about is for the Helsinki public aquarium, and it's filter volume is, from what I understand, several thousand liters - it is easier to keep these things going on a larger scale, because it is more stable. They also have calibrated equipment to "feed" the bacteria in the anaerobic system.

Plants, unless kept under very ideal conditions, do not grow quickly enough to consume enough nitrate to keep on top of a heavily fed tank with large fish.

My suggesstion would be to do bigger and more frequent water changes. Also check the tap-water, and if that is high in nitrate, an RO system is probably required to reduce the nitrate [or other de-ionification system]. There are ion-exchange systems that specifically target nitrate, but it gets very expensive quickly. An RO system will also reduce the pH by removing the calcium carbonate and other minerals that pull the pH higher. Just beware that if the KH value goes low, you need to add a KH buffer - I use one meant for marine systems, but there are different substances on the market. You will, besides from a large enough RO unit, need a pH meter and a TDS meter to check your water regularly.

--
Mats

[2wheelsx2]

I agree with Mats on the plants. You'd have to do CO2 injection with high lights with a huge amount of plants (like 40 or 50 lbs worth) to be able to make a dent at that nitrate concentration. Better off to do more water changes.

[Bas Pels]

As nitrate is formed due to digesting of protein, and oxygen is needed for this process, being formed into CO2, no CO2 injection would be needed

in fact, CO2 injection is only 'needed' in circomstances where far too may plants are kept with too little fishes. obviously, introducing fishes would be a nicer solution

But still, these plants would still require a HUGE amount of light, most likely more than possible

It's easier, more cost effective and friendlier for your fishes to just change water

[2wheelsx2]

Since his problem is a net production of nitrate, adding more fishes to generate CO2 is not a solution. To generate that kind of CO2 needed to grow plants sufficient to consume nitrate overall, you'd have to stuff enough fish into the tank to deplete the O2 long before you get enough CO2 into the water. And if you aerate enough to bring in the O2, you would offgas the CO2.

But that argument is moot since we both agree the simplest solution is to do water changes. I would think a continuous water change system can be implemented a lot cheaper and be a lot less work than trying to grow plants with more lights and mass producing plants.

[Redtailrob]

More water changes it is then.
I currently do 30-50% every other week but could increase that to weekly. Heck that's allot of water but needs must.
Fish come 1st.

[MatsP]

I would say same every week will help it. Keep testing the nitrate level on the tank.

--
Mats

[Redtailrob]

Will Do Mats.

Looking into upgrading the Tank size too or converting too a larger Pond. Will see what i can do.
Weekly WC's it is & have also removed one or two of the other fish out to decrease the load on the system.

[PeterUK]

I currently do 30-50% every other week but could increase that to weekly.

I would have thought that you should be doing AT LEAST 20% every other day or 10% daily as you have some of the 'big boys'.
The more water you change the more the fish will appreciate it (obviously within reason)
I change upto 70% on some tanks every other day, changing a total approx 150G per week on all of my tanks.
The only reason that I can think of why I would change water every other week is if I was on holiday or seriously ill and couldnt do it.

[andywoolloo]

i do 50% every 4th day on all my tanks. just for info.but I do not have big guys.

[Bas Pels]

Since his problem is a net production of nitrate, adding more fishes to generate CO2 is not a solution. To generate that kind of CO2 needed to grow plants sufficient to consume nitrate overall, you'd have to stuff enough fish into the tank to deplete the O2 long before you get enough CO2 into the water. And if you aerate enough to bring in the O2, you would offgas the CO2.

This is not the case, after all, the very air we use to increase the O2 concentration in the water does contain CO2. CO2 does dissolve easily, and will result in 5 mg/l CO2. The more watermovement, the more certain you will be of reaching this value, whether starting with water containing too much CO2 (still water without plants, and lost of fishes, or water with added CO2) or too little CO2 (a tank with lots of plants, with little fishes)

Aquatic plants evolved in water with this 5 mg/l, and will therefore without any doubt be able to get what they need. This same amount wil lbe acceptable for fishes, as it is the amount they evolved in too.

Water is not comparable with a bag as in 'where there is O2, this spot can not contain CO2'. Both gasses dissolve in water, but not the same way, and therefore, a spot for O2 will not be usable for CO2.

However, I don't think plants are a good way to decrease nitrate levels, but I do think they are a good way to prevent the increase of these levels partly

[2wheelsx2]

This is not the case, after all, the very air we use to increase the O2 concentration in the water does contain CO2. CO2 does dissolve easily, and will result in 5 mg/l CO2.

Problem is if your uptake is > 5 ppm. And to have high uptake in nitrates/ammonia/nitrate, the very first ingredient is CO2 and then light. So at 5 ppm, you're limiting CO2, no matter how much light and nitrate you input. I just attended a very interesting talk on this very subject by Tom Barr last night (http://www.barrreport.com).

But as you said, it's not going to work in this case. The amount of plant growth needed for this uptake would far outstrip the cost of the water changes in this tank.

I just found out this relationship the hard way this last month. I bumped up the CO2 a bit by cleaning the diffusers and pruning my plants (which increased circulation as you mentioned above) and my nitrates bottomed at zero at my usualy dosing rate of 30 ppm a week and my java fern all started developing holes. I am now increasing my KNO3 dosing to reach 15 ppm every other day for a total of 45 ppm nitrate target a week. I have a lot of fish in this tank, so if you put enough light and enough CO2 into the tank, it's possible to reach zero nitrate, but the amount of work needed is probably not fruitful, unless your object is partly to grow plants (I see mine). I harvest 1 to 2 pounds of plants out of that tank a week.

Actually, maybe I am jumping to conclusions. Do you currently have a non CO2 injected tank that is reaching zero nitrates? If so, I'd love to see it. I've seen plenty of tanks that have this characteristic, but it's usually a tank full of tetras, not large fish.

[Bas Pels]

I don't think I got a 0 nitrate tank.

I got 31 tanks, but as I'm mostly a cich lid keeper, and the cich lids I keep are large, I would doubt any of my tanks is low on nitrates.

although, I got a 70 * 75 cm tank, al grown over with Sagittaria, housing 10 Otocinclus and a few Phalloceros caudomaculatus, all from Uruguay. But I never measure any tank, and you will say 'see, a small-fish tank'

HOWEVER

If you have a tank with a lot of flow, all CO2 taken from the water by the plants will be replaced by CO2 from the air, as equilibrium is 5 mg/l of CO2 if the water contacts the air - and movement of the water helps a lot reaching said equilibrium

Nitrate - or other nitrogenous products - are not coming from the air, so the nitrate - CO2 balance will - ultimately - reach 0: no nitrate, and still CO2 in the water

[2wheelsx2]

My 125 has 45 plecos including 3 Royals, and a 10" Chocolate Cichlid, 30 cories and 3 EBJD's ranging from 7" to 5". I'm just relating my experience. It's not a light load and I'm bottoming in nitrates. Just relating my personal experience.

My point was that it's possible, but not economical. Whether you choose to do it or not is a different story. If you have cichlid tanks, your plants aren't your first priority anyway. And I think MatsP and others have already said that you can have a fish oriented tank or you can have a plant oriented tank. Just because I choose to do it a different way than you doesn't make my experience invalid.

If you don't want to inject CO2, don't. But don't make it out to be some root of all evil.

[2wheelsx2]

Nitrate - or other nitrogenous products - are not coming from the air, so the nitrate - CO2 balance will - ultimately - reach 0: no nitrate, and still CO2 in the water

it's only going to reach zero if your uptake is higher than the production, and at 5 ppm, if you add enough light to reach max uptake, your limitation is CO2, just as I said in my other post. Plants need 3 things to grow, light, nutrients and CO2. So in your example, the limitation is what you can achieve with atmostpheric CO2.

[Bas Pels]

If you don't want to inject CO2, don't. But don't make it out to be some root of all evil.

If you keep your plant tank free of fishes, do whatever you want

CO2 over 5 mg/l = torture for any fish in the tank. I think the odea of keeping fish in a tank is to provide them with what they nood for being well, and that means as little CO2 in the water as possible

adding CO2 to water with fishes IS the source of all evil to me

[Line]

Hello

You could use emerse plants => no worries about co2 then

I promise you - I had absolutely no nitrate in this tank. Actually.. emerse plants do a much better job.
And the roots are looking good and very naturally too.

Best regards
Line

[Viktor Jarikov]

Very nice discussion guys, educational for me. Thanks. It's ok to agree to disagree, I guess.

Line, that's simply bea-u-u-u--u-u-u-u-tiful! Nice, nice, nice stuff. This must look so natural and relaxing! We grow these kinds of ivy in large, shallow pots but they LOVE stretching their roots in the water, like when they are positioned above our outdoor pond waterfall. Do you have to trim the roots every now and then? Do they have some roots in soil?

[Line]

Hello

Thank you very much.
The Roots have no soil, they are just swimming in the water.
I don't trim the roots. It's funny - but they don't get that massive at all.

Here you see the beginning and the trick

fraoven.jpg (201.41 KiB) Viewed 5460 times

The emerse plants profit from the aquarium light too. I just removed the reflectors and changed the topplates into glass.

They were growing like *****

My setup changed since then, but I still use the Scindapsus.
Btw one shouldn't damage the roots. They contain a little oxal acid.

Best regards
Line

[Reginator]

A second cannister filter full of nitro-zorb resin would kick those levels right down......

[MatsP]

A second cannister filter full of nitro-zorb resin would kick those levels right down......

Yes, in the short term. But it's not a permanent solution (unless the nitrazorb is replaced/regenerated).

--
Mats

[Reginator]

Indeed, but rinsing the resin is neither complex nor requires any special substances. A double-load for the filter would allow you to cycle through them, recharging one while the other is working until the levels drop to where you want them. Once you have them eliminated you only need to fire up the resin filter part-time to keep them out....

[MatsP]

Ehm, you just RINSE IT? The web says you recharge it with table salt - which is indeed pretty simple...

--
Mats

[Bas Pels]

The problem is, however, anything recharged with salt will, in use, loose the salt again

In a malawitank, this will not be a problem - but with fishes from very soft water? I'd rather use plants and water changes

[Reginator]

Hmm, I'll have to investigate a bit but I thought the salt was used to somehow extract the nitrates stored in the resin and isn't absorbed. The stuff I have is rinsed in a brine solution for a while, then rinsed off in osmosis to get rid of any salt....

[MatsP]

I'm pretty sure it's a ion-exchange unit, similar to how a water softener works (also using common salt, but swapping calcium carbonate for sodium chloride rather than replacing nitrates). So, yes, I think Bas is right. Now, if the nitrate level is, say 20 ppm, it's not really a big issue to add 20 ppm sodium chloride.

Searching for "commercial nitrate removal ion exchange" finds this rather useful article on ion exchange in general, and it talks about nitrate removal a little past half-way down - it doesn't say much about how it works, but it shows that ion-exchange is a plausible method ...

http://www.excelwater.com/eng/b2c/ix.php

And this page describes, in the second part of the answer (waste water nitrate removal) that a Type II resin is the type of resin used in the Nitra Zorb product - it may not be a Dow product, but functionally, I'd expect it to be similar if not the same:
http://dow-answer.custhelp.com/app/answ ... of-nitrate

--
Mats

[apistomaster]

Ideally, having a settlement basin prior to any water entering a filter system is best because it collects uneaten foods and is drained frequently thus reducing the food available for nitrifying bacteria but this is usually only practical in an aquaculture setting.

I include removing the mineralized detritus that accumulates in the sumps of wet/dry filter systems at the same time I am making my water changes. Even this detritus still has food available for further nitrification. Everything than reduces the available excess food supply of the nitrifying bacteria is best kept as low a possible but only water changes can minimize nitrate build up. Using RO water as replacement water after some partial water changes periodically will also help keep the nitrate accumulation lower over time.

[Bas Pels]

I'm pretty sure it's a ion-exchange unit, similar to how a water softener works (also using common salt, but swapping calcium carbonate for sodium chloride rather than replacing nitrates). So, yes, I think Bas is right. Now, if the nitrate level is, say 20 ppm, it's not really a big issue to add 20 ppm sodium chloride.

Mats

Not having any experience with nitrate exchange units, but having sudied chemistry, I rather comment on 20 ppm nitrate - 20 ppm sodium chloride exchanging

All these exchangings are affinity based. That is, if chloride is kept much more lousely than nitrate - than the binding of 1 nitrate might losen up 2, 10, 50 or even more chloride

Therefore it could be - but I don't have the munbers - 20 nitrate is exchanged for perhaps 1000 chloride. But all I can do is warn for a possibility, as I never used the stuff (and my fish are very salt tolerant )

Chemistry can be fun, but I'd say measure first, before you use these stuff with sensitive fish.

[MatsP]

Another Dow document here shows a 1:1 charge balance between the different ions on the first page (unfortunately, you probably have to download all 2.7MB of it) [charge balance means that a Ca2+ will be replaced by 2 Na+ ions, for example].

So we're sort of both right, as 2 Na+ is not exactly the same as 1 Ca2+ in ppm, but it's not 20 or 100x either...

--
Mats

[Viktor Jarikov]

My limited understanding is that ion-exchange organic-polymer resins are based on the, well, exchange of ions, that is electrically charged particles. Where mobile cations (positively charged particles) are exchanged, such as, Ca2+, Mg2+, Na+, K+, etc., a negatively charged polymer resin is used having anionic groups in the polymer chain/pendant/structure (immobilized negative charges), such as RSO3- or RCOO-, RO-, or species with a complete electronic core, etc. And vice verse - except, I do not think they immobilize metal cations but rather use species with complete electronic core, e.g., R3S+ (sulfonium cation), phosphonium cation, etc. covalently attached to a polymer chain. It must be a 1 charge for 1 charge exchange for it is simplest electrostatics.

If chelation mechanism is used, it is also usually one for one (in charges and chelation sites).

If zeolites (special extremely porous minerals) are used, the situation is different, these I opine are based more on affinity as this does not involve simple electrostatic forces and the whole salt molecule (cation and partner anion) is bound at the zeolite surface as to keep the overall charge neutral.

Like Bas, though, I claim no expertise in ion exchange. Anybody can look at Wikipedia and learn far more and better than said here.