Ideas on setting up and maintaining a black water tank

[Jobro]

Hey everyone,

I plan on setting up a blackwater breeder for my Ancistrus Dolchiopterus. They will only spawn in low PHs anyway and I feel like a real blackwater setup could be quite magnificent.

The rainwater I use has usually a PH of 7 or lower to begin with (KH<2, conductivity <50ms). However, I would like the tank to stay at around PH6 or lower for most of the time.

I am looking at ideas to have a self sustaining low PH in this tank.

Well the obvious way would be to hold back on waterchanges. But I would like to keep doing waterchanges every week or every two weeks. Any waterchange could possible raise the PH for some time.

The second idea would be filtering over peat. And I am probably going to partly rely on that. But I don't like the idea of prefiltering over peak outside of the tank and than add that acidic water during waterchange. I tried it and I came to the conclusion that it was mostly a mess and most of the time the PH inside the tank would still be quite different from what the prepared water had. So I will have the peat inside the tank and change it every 1-2 weeks or that. I will also be using rooibos tea to get a nice taint to it.

Another Idea that I am looking into right now is the use of sphagnum moss. It lives in acidic environments with very low nutrients, just like a blackwater tank would offer. It will reduce hardness by using up minerals and emits hydrogen ions, helping to create an acidic environment fitting to it's own needs. It lives mostly emersed though, so I might need to plant them in a kind of refugium. Not sure how big the effect actually might be. I will need to test it first. I don't even know if it can be cultivated at higher temperatures at all.

I also feel like using the bark of some trees could help maintaining low PHs. It's pretty easy to get oak bark around here.

Anyone has experience with coconut fiber? I read it contains some tannins as well.

So If anyone has long time experiences with keeping water dark and accidic, I would love to hear about it.

[Shane]

The main problem I have encountered is avoiding big swings away from soft, acidic conditions at every weekly water change because my tap water is hard and alkaline. My solution was to take an empty 20 gallon tank and fill it 1/3 full of oak leaves. At water change time I would drain the tank with blackwater fishes 50% and replace it with water from to 20 gallon with leaves. The water was already made black since it had been soaking the leaves for a week. I would then fill the tank with leaves back up with tap water mixed with some rain water.

You do not have to use oak leaves in the soaking tank. Anything that lowers pH and adds tannins would work. I just have infinite free oak leaves from my yard. The only real drawbacks are that you are basically doubling water changes and you have to "sacrifice" a tank to make the blackwater. Also the size of your blackwater tank will be limited by how much water your soaking tank can produce each week as you ideally do not want to drain the soaking tank more than 50%.
-Shane

[racoll]

In a tank with lots of bogwood and using rainwater, the pH will naturally drop low. Maybe a few alder cones added would help too.

Just treat it normally, but the key is to do smaller more regular water changes to keep the tank stable, maybe no more than 10-20% at a time.

[Bas Pels]

A friend of mine once called me to explain his tank. I've studied chemistry, so I assumed it could not be that hard.

The situation was, he had a caqnnister filter filled with peat, with a second one with a more regular filling, and the tank was filled with RO water. the pH? Stable at 4.

A pH of 4 is in a normal tank never stable, a stable pH needs buffering (in order to keep this post from getting too long, I'd refer to Google) and the only buffers working in a tank are CO2 - HCO3-. failing under pH = 5 and the phosfate system (H3PO4 - H2PO4- - HPO4-- PO4---) which will not be able to do much as we need to keep the levels of phosphate low

However, what I think he did was create a working peat buffer. That is, if half your peat is active as an acid and the other half has done this, the peat will buffer the pH. But, normally, waterflow through a sufficiently large amount of peat is too low to buffer a tank. BUT if you are luchey, the flow through the peat can be sufficient to have the canister buffer the tank.

Bogwood in the tank will, obviously, help.

If you manage to get a working copy of this, and your water with a KH of 2 is soft enough in this aspect to try this, all yoou need to do is prepare the water you use to change water. With peat, that is.

The water will color. Some say that is a disadvantage, but I myself like that color

[TwoTankAmin]

I have run tanks at 4.2 pH in a stable fashion for months. It involved the use of ro/di, muriatic acid and a combination of catappa leaves, alder cones in a filter which was occasionally supplemented with a bit of peat early on. However, I find peat to be messy and do not use it any more.

That tank was gradually raised to 6.0 -6.5 as its normal operating range.

For me the key is reducing KH in order to hold the tank at any desired acid level. I get the majority of my staining from brewed rooibos. But both the cattapas and alder cones help in this respect. I also use a bit of Kent Black Water Expert.

I buy the cones and cattapas in bulk wholesale which makes them more affordable. $100 worth of alder cones is a lifetime supply.

The most important part of all of this is my continuous digital monitor which gives me readings on TDS/Conductivity, Temperature and pH. I move the probes to the new water container when preparing it to know exactly what I am getting.

[Jobro]

Thanks everyone for your input. Lots of good experiences for me to apply on my own project.

In the meantime I did some experiments with different substances.

I put Catappa leaves, Alder cones, Walnut leaves and Beech bark into different cups of my rainwater.

The rainwater is actually a little alcalic right now. Don't know why. The chemistry seems to be different in winter compared to summer. PH prior to the treatment was 7.40.


9 Alder Cones: Darkest water with a pretty low PH of 5.13

2 Catappa Leaves: brightest water but lowest PH of 4.96

2 Walnut Leaves: highest PH 6.95, not very efficient

Some pieces of Beech Bark: PH 6.90, not very efficient either

More tests to come.

[Shane]

Great job with the testing. We need this kind of empirical information. Can you try oak leaves?
-Shane

[Jobro]

Too bad, that I missed collecting oak leaves during autumn, I will need to look for some and see. But they are probably not as efficient after having been soaked by snow and rain now So it is up to what I can get right now. hopefully I can get some.

I will try oak bark for sure though. Peat. Sphagnum/peat moss dried and alive. Some Rooibos (I know it will not alter the PH, but we can get a sample for the taint I guess). Coconut fiber if I can get some good. Anything else? maybe ceylon cinnamon?

[Jobro]

Was out and found some Oaks that still had dry leaves on them. I collected some and will make my tests.

[TwoTankAmin]

My problem with relying only on botanicals for altering parameters is that there is a lack of control. In nature the volumes involved are great unlike in a tank. This results in a fair degree of stability. Even with dry and rainy seasons the changes tend to be withing specific ranges.

In a tank things are on a much more finite and small scale. How many catappas will we add and when. Do the leaves we use this week have the same content as the ones we use next week? Will they become the same mulch muck on the substrate in the same amount of time?

Perhaps the most interesting things I have learned in this respect is that the fish I have kept in such acid conditions are able to handle in excess of a full point drop in pH which occurs in under 5 minutes. I watched this happen in a bunch of tanks at a seller's facility and I have implemented it in my own tanks since then. I would never attempt this in the other direction however. I consider the greatest potential issues in low pH tanks are an unwanted and unexpected rise in either the pH or the TDS. While I believe that the latter is more relevant in terms of how it can adversely affect the fish, terms of the nitrifying bacteria, I am more concerned with the pH.

The nitrogen cycle is still working even at 4.0 pH, but not in the same way as it does above about 6.5 pH. The parameters for ammonia/ammonium at acid pHs are way different than what we expect in most tanks. This means the ammonia oxidizing microorganisms involved are often different and/or less efficient at converting ammonium to nitrite. This is important in an acid water tank since the microorganisms at work there and those in water approaching neutral and going towards rift lake numbers are different and/or simply function less efficiently.

The risk is in allowing an acid water tank's pH to drift up too much to the point where it disrupts the established cycle. I cannot imagine maintaining such a tank without a constant monitor on it. I started out using test pens and within a few months realized I needed to step things up. It makes it so much easier to insure stable parameters.

One last note. I do the acid water for Altum angels which I have no illusions about spawning. I am nowhere near that good. But I really love Altums and it took me many years before I was willing to attempt keeping them and a few more before I managed to keep them alive for any length of time. I am not certain how catfish would work in my system but I have H. contradens in my Altum tank. The plecos do not spawn.

[Bas Pels]

@ Jobro

Very interesting data. I don´t think you weighed the leaved, but the amounts are somewhat similar?

More of us should do this kind of thing, and than most likely we will get some unexplainable differences - something like oak is not oak

That can be explained, the native American oaktree (Quercus rubra) is a way different one than the European ones (also Quercus species), with different bark, leaves and oaks - similar observations for other trees might happen

[Jobro]

@ Jobro

Very interesting data. I don´t think you weighed the leaved, but the amounts are somewhat similar?

No, I did not weigh them. I just want to give some pointers to what seems to be effective on lowering PH and what is less effective. As you stated, the results will vary a lot depending on your own ingredients, so going for very precise data seemed not too usefull to me. I am more interested in giving a rough overview.

Meanwhile my Ancistrus Dolchiopterus seem to not care too much about blackwaters or not. They spawned in my 400L community tank. I did a quick check on the water parameters.

Temperature: 27.3°C
PH: 6.1
Conductivity: 222ms

[Shane]

Chris,
Your comments above about using botanicals are why I eventually went with the empty "soaking" tank. That way I could quickly test that the soaking tank was at similar parameters to the aquarium with fish before water changes.
-Shane

[Bas Pels]

Good luck with the eggs. I do hope they hatch, but sometimes fish lay eggs regardless the water Chemistry, and the eggs immediately die.

If hatching fails, or dad kicks them out, the water might be the clue

[TwoTankAmin]

As an aside, my experience has been that it is the conductivity/TDS which is the key. It is difficult to have acid, especially very acid, water and higher numbers for conductivity/TDS. In working with altums I never bothered with staining or much below a neutral pH, but I did have TDS in the 20 ppm range. I was using about 75-80% ro/di.

The other thing I learned was that the properties of rooibos are likely more beneficial than those in oak leaves. However, rooibos will do nothing to soften the water nor lower the pH. If anything, you might see a .1 rise. However, the nature of the rooibos are such that it is a waste to buy an organic version. It was explained to me that the sort of things that would prevent it from being considered organic would kill the plant. It is so fussy that it will grow on one side of a hill but not on the other side.

There appears to be a great deal of research into Aspalathus linearis (rooibos). I have not found anything dealing with its use in aquariums but there is some involving marine fish. Among other things, it is loaded with antioxidants.

Edited to correct grammar, spelling and a few omitted words. I should not type with my glasses off, sorry.

[bekateen]

I am really fascinated by this thread, but I feel like my own experiences are too limited and whimsical (random) to be helpful. I'll just follow you all. Thanks.

[Jobro]

Chris,

I am doing a test with rooibos right now. I got some surprising data and was actually going to ask you about this.
PH went from 7.40 to 6.7.
But the strange thing is, that conductivity went from 20ms to about 440ms
Maybe this is just a side-effect of too much rooibos on too little water?

Similiar happenings with ceylon cinnamon.
PH went from 7.4 to 6.1 (did not expect that, right now cinnamon seems to work better than the oak leaves I found)
but conductivity from 20ms to 220ms!

The other testcandidates have way less effect on conductivity. (peat from 20ms to 50ms e.g)

[amiidae]

@Jobro,
Whats your tank size ?

Had similar challenges trying to maintain the consistency of the pH in my tanks too. So I stick with commercial products to maintain the pH level.

This is what I do for my smaller-size 40L tank.
1) I use Aqua soil as base. Like this.


2) Fix the frequency & the percentage of ea water change.
3) Constantly adding the same amount of blackwater extract during each water change.

[TwoTankAmin]

I brew the rooibos and add the liquid. I use about 2.5 tablespoon of rooibos in a quart of boiling water. I pour this into 20 gal rubbermaid with batching water. It has the probes from my monitor in it during water preparation. I add about 1.5 tablespoons of Kent Black Water Expert as well. Finally, I add muriatic acid to get the water down towards 5.5 pH. The exact number depends upon the tanks readings at changing time. The tank is a 55 gal. (I am planning to upgrade this to a 6 ft tank in the near future.) I do notice a small rise in the TDS from the acid.

I have never seen the TDS rise as a result of the tea being added but have seen the pH go up .1. I prefer using TDS to conductivity. I seem to grasp the ppm numbers more instinctively than microsiemens. The changing water tends to batch up between 50 and 60 ppm TDS.

One of the interesting properties of rooibos is it has a calming effect on the fish. With newly arrived altums this is often a great benefit. Once I figured out how to keep altums alive longer term, I have really only lost them due to health issues on my part. The fish do need weekly water changes. I was forced onto an every 3 week schedule for 2 months and that cost me most of them.

My experience is that the alder cones do more to lower the pH as does peat. I find the latter too messy. One can use rooibos in a bag in one's filter, but again, too messy for me. It is bad enough replacing the bag of alder cones when it has turned to mush. But again, the real key to lowering one's pH is to remove KH from the water.

One note- I cannot put my probes into the changing water when I am batching it when it holds only the ro/di water. The unit freaks out. I need to add warm tap water to get it up to temp and to some level of pH which is a "real" reading and TDS which is not approaching 0 ppm. Then I add the other ingredients.

[Jobro]

@Jobro,
Whats your tank size ?

Had similar challenges trying to maintain the consistency of the pH in my tanks too. So I stick with commercial products to maintain the pH level.

This is what I do for my smaller-size 40L tank.
1) I use Aqua soil as base. Like this.


2) Fix the frequency & the percentage of ea water change.
3) Constantly adding the same amount of blackwater extract during each water change.

I know, that using mineral acids is one way to go. I wanted to try a path of a more natural, self sustaining blackwater tank.

[Jobro]

I brew the rooibos and add the liquid. I use about 2.5 tablespoon of rooibos in a quart of boiling water. I pour this into 20 gal rubbermaid with batching water. It has the probes from my monitor in it during water preparation. I add about 1.5 tablespoons of Kent Black Water Expert as well. Finally, I add muriatic acid to get the water down towards 5.5 pH. The exact number depends upon the tanks readings at changing time. The tank is a 55 gal. (I am planning to upgrade this to a 6 ft tank in the near future.) I do notice a small rise in the TDS from the acid.

I have never seen the TDS rise as a result of the tea being added but have seen the pH go up .1. I prefer using TDS to conductivity. I seem to grasp the ppm numbers more instinctively than microsiemens. The changing water tends to batch up between 50 and 60 ppm TDS.

One of the interesting properties of rooibos is it has a calming effect on the fish. With newly arrived altums this is often a great benefit. Once I figured out how to keep altums alive longer term, I have really only lost them due to health issues on my part. The fish do need weekly water changes. I was forced onto an every 3 week schedule for 2 months and that cost me most of them.

My experience is that the alder cones do more to lower the pH as does peat. I find the latter too messy. One can use rooibos in a bag in one's filter, but again, too messy for me. It is bad enough replacing the bag of alder cones when it has turned to mush. But again, the real key to lowering one's pH is to remove KH from the water.

One note- I cannot put my probes into the changing water when I am batching it when it holds only the ro/di water. The unit freaks out. I need to add warm tap water to get it up to temp and to some level of pH which is a "real" reading and TDS which is not approaching 0 ppm. Then I add the other ingredients.

maybe I will need to get a TDS probe then.

Don't forget about that super good scent, that rooibos emits

As to removing KH, my rainwater is often below KH 1° during summer, that's why I get quite low PHs(~6) in all my tanks pretty easily. During winter it sits at around KH 2° and I get mostly neutral waters in my tanks. Some tanks, like the community tank, manage to keep the PH lower even during winter. Not sure how it does that. As it is just another planted tank with driftwood. No special treatments. I have a hunch, that the huge amount of snails are using up all the minerals in the water and are a key to lowering KH.

[b.reder]

Several years ago, I was interested in an acidic dark water tank. I tried the peat balls in a bag wedged in my HOB filters. It worked. However I live on an organic pomegranate farm. If you have ever picked and juiced a large amount of poms, you would notice that the tannic acid in the shell quickly turns your bare hands a dark brown. I collected a few dry shells and put them in a small tub of water. Wahla! Dark acidic water. I, however, did not follow the system for a long time. I did put the shells in a cloth bag and again, wedged them in to my HOB filters.

[Lycosid]

For a completely different, possibly stupid, way to make blackwater, I've thrown instant decaf coffee into the tank.

The pros of this approach are that the room smells like coffee, it's cheap, and it's massively unpretentious. The cons of this approach are that the room smells like coffee, it looks cheap, and people may accidentally drink the fish tank water. However, since it's instant coffee, it will actually taste worse than regular tank water.

[bekateen]

...I live on an organic pomegranate farm.

You live on a pomegranate farm? You lucky duck! My family loves pomegranates. We've got one lone tree in our front yard. A season may yield anywhere between 80 pounds of poms and 2... not 2 pounds, 2 poms.... and occasionally zero poms in a year. I don't do anything fancy to maintain the tree other than annual trimming and every few years regular yard fertilizer (the tree is in my front lawn)... Although I'd like a better yield from year to year, I don't want my yield to exceed what I already get in good years - more than I can handle (like baby BNs).

If you have ever picked and juiced a large amount of poms, you would notice that the tannic acid in the shell quickly turns your bare hands a dark brown. I collected a few dry shells and put them in a small tub of water. Wahla! Dark acidic water.

Do you think pom pealings would be eaten by plecos (maybe a source of dietary pigments to enhance color in juvies)? I can tell you that my plecos NEVER eat potato peals... not that they are the same, but maybe plecos don't like the bitterness (IF they can taste bitterness, that is).

Cheers, Eric

[b.reder]

ERIC-
Just remember that, in humans, too much tanic acid is toxic to the liver. On the other hand, you might be onto something. If you have an extra tank and plecos, try some and let me know. Yes, I am lucky- 300 pom trees and 100 lemon trees. I just planted some grapes for personal consumption.
- Barry

[bekateen]

Just remember that, in humans, too much tanic acid is toxic to the liver.

Indeed. I'm not wanting more poms at a time, just more consistency year over year. That said, the tannins are in the skin, not the fruit (aryls, if I spell that right), som my own consumption should be fine AFAIK.

Enjoy your grapes.
Eric

[b.reder]

Yes- The tannins are in the skin and that is what I used for acid dark water. My trees are the "Wonderful" clone. This is the common commercial variety. Different clones yield different results. Perhaps a regular water and fertilizer regime would give more regular results. On the other hand, you are quite north for poms afaik.

[b.reder]

Was it your mayor who announced a $500 per month give away to the "poor" no proof necessary?

[b.reder]

The pros of this approach are that the room smells like coffee, it's cheap, and it's massively unpretentious. The cons of this approach are that the room smells like coffee, it looks cheap, and people may accidentally drink the fish tank water. However, since it's instant coffee, it will actually taste worse than regular tank water.

Lycosid- My wife's father's people are from Lincolnton and Hickory, N.C. The folks we met there might want to open a boutique fish tank/ coffee shop.... if you franchise it.
-Barry

[bekateen]

Was it your mayor who announced a $500 per month give away to the "poor" no proof necessary?

Yup, that would be my mayor. The $500 has no strings attached. I don't qualify, but if I did, I'd buy some nice

L174

or maybe

Corydoras pantanalensis

.