Keeping low pH

[raymond82]

Hi,

I was wondering how difficult it is for a relative beginner to keep an aquarium at a pH of 5 or even lower. From what I understand, some of the species that I would like to keep in the future (paucisquamis, T. candidi, iniridae, elizabethae) require such low levels to breed.

When keeping fish at such low pH, how is this best done? Filtering my osmosis water with peat works really well, but how can I maintain water stable at such low pH? And how can I avoid a pH drop that might kill the fish?

Thank you!

 

[electric eel]

hi raymond,i know a lot of the guys(the organic non chemical guys) will disagree but i had really good luck maintaining a ph between 4.7 and 5 with sodium bisulfate(its really inexpensive too).i would add 200 grams of sodium bisulfate to one gallon of distilled water.i added the stock solution one drop at a time until i reached my target ph.i was using ro/di water that i brought back up to 25ppm or so with ro right by seachem.i bred dicrosus filamentosis(and a few other fish) like this so i know it is safe.a couple guys on the forum expressed the opinion to me that it might elevate NaCl levels and adversely affect the fish but i found that increases in Na Cl levels were negligible.i was told that sodium bisulfate wants to buffer to around 4.7 by a chemist but i cant find any info on the internet to confirm this.you will need a fairly reliable ph meter and paraphenalia(calibrating solution,storage solution etc) you need a tds/442/nacl meter also(in my opinion)i always liked to make up my water in a dedicated 55 gallon tank and let it rest before i used it but honestly it seemed like the ph was pretty stable as soon as you mixed it up.i would check it over the course of a couple days(before use) and didnt notice fluctuations in ph.i wonder if an acetate buffer solution would be safe to use with fish.the amount of buffer solution required for ro/di water might be low enough that it would be safe to use for fish but i dont know.if so you could very precisely buffer the water to any values between 3 and 6 that you wanted.it might be worth experimenting with a readily available,cheap fish to see if it would be okay.DW1305 might be able to find out for us.good luck!you can find a chart for making up acetate buffer solutions at delloyds.50megs.com by the way.

 

[dw1305]

Hi all,

When keeping fish at such low pH, how is this best done? Filtering my osmosis water with peat works really well, but how can I maintain water stable at such low pH? And how can I avoid a pH drop that might kill the fish?

The problem here is not really with the water, but the pH scale. Because pH is both a log scale and a ratio, as you get towards pure H2O, pH becomes much less stable, but it doesn't matter. There is some more description in your older peat thread <http://www.apistogramma.com/forum/index.php?threads/sphagnum-moss.12164/#post-66319>, and you really need to read this thread <http://www.apistogramma.com/forum/i...wer-ph-seachem-discus-buffer.11214/#post61157>.

cheers Darrel

 

[electric eel]

it all sounds pretty complicated to me darrel.what do you do if you are keeping fish that like clear water with a really low ph.i would think that would rule out peat.i know from experience that discus buffer from seachem works really well but it is expensive and obviously a higher target ph then you would want for some of the fish mentioned above . i can't believe that it isnt possible to make up a fish safe lower ph buffer .this is a recurring theme i see on a lot of forums.that is maintaining a really low stable ph.as i said above,i was able to maintain relatively stable ph's with the method i used and i cant believe that there arent chemists out there that have solutions for this problem.maybe they are all working for seachem(this is a feeble attempt at humor) i am guessing the reason no one has marketed a product for this is that there is limited demand.

 

[Mike Wise]

I keep low pH stable by putting only 2 or 3 apistos in a relatively large tank + regular water changes. As for clearwater apistos, the tolerate pH fluctuations better than blackwater species. Their environment will vary more in pH more due to seasons, rainfall, and other water influences. Blackwater is always getting more organic input into the system. This tends to buffer the system more. My guess is that this is why clearwater apistos are much easier to breed than blackwater species. For blackwater, I prefer to use a more natural method to lower the pH: peat/leaves in r/o water.

 

[gerald]

Are there really any fish that need low pH and low organic matter? I didn't think such conditions existed in nature, other than maybe right at the mouth of CO2-saturated spring. Organic matter (leaves and branches) wont decompose completely in soft acidic water, so if water is soft and acidic it soon becomes tannin-stained (unless there's no trees around, in which case there's probably no fish) .

EE - is there some drawback or limitation to your NaHSO4 buffer method? At the point where you've added enough to work effectively as a buffer, what's your conductivity? I suppose you'll need to replenish it as the plants consume the sulfate.

 

[electric eel]

my experience is too limited and not even remotely scientific enough for me to make any definitive conclusions gerald.i only used around 60 drops of my stock solution to reach around 5ph in a 55 gallon tank of ro/di water and it didnt noticeably impact conductivity or nacl levels.all i know is it worked.i had trouble getting the ph really low with just leaves and i thought i remembered apisto dave or someone saying that they got moderately low ph 's using leaves etc but that it was hard to get it down really low without chemicals. i think there are a lot of relative novices out there(like me) that dont care a lot about the science behind the process but would really like someone to come up with an relatively easy formulaic method for maintaining low ph water.maybe a reliable safe method doesnt exist but i really dont believe that.i usually only had a pair or trio of fish in at least a 20long and was doing regular water changes so maybe thats why i didnt experience any dramatic dips in ph.its a really extreme example but i think there are fish in some of the caves in mexico that the ph is down in the 3's and water is clear.i think they said on tv that the water dripping off of the ceiling of the cave would burn your skin.

 

[raymond82]

Hi,

Thank you for all the input!

Electric eel, thank you for the elaborate description. We actually have Discus buffer around somewhere, I tried it once in a separate container but it increased the conductivity so I discarded it as an option. I might try your method to see what pH I could get stable and what the conductivity would be. However, I'm more tempted to use a more natural way and I found that filtering osmosis water with peat is highly effective (I managed to get the pH to 4.5).

The main worry I had was whether with this peat filtered osmosis water I would run the risk of having to many pH swings, since there will hardly be a KH buffer. I've read in many places that people use pure peat filtered osmosis water and I was wondering how to handle this (for instance, do you monitor the pH more closely to detect changes?).

Darrel, thanks for pointing me to this thread. I have bits and pieces of knowledge gained from this website in my memory but sometimes I find it hard to put them together or remember where I had seen them.

during the
cycle the photosynthetic pH will fluctuate widely (as you suggest) from ~pH4 to ~pH9. This doesn't effect the fish in the way that it would if the pH change was occurring in buffered water

That is what I want in the tanks, a stable, resilient environment. I'm pretty sure that this is much more important than maintaining than any particular pH value etc.

These two quotes sum up my complete dilemma, since if I want to try to keep extreme soft water/low pH species I wouldn't know how to meet both demands.

Mike, I keep my apisto's in 40 to 50 litres, usually in pairs or trio's and I do weekly 25% water changes. Would that qualify as relatively large tanks and regular water changes?

As for clearwater apistos, the tolerate pH fluctuations better than blackwater species. Their environment will vary more in pH more due to seasons, rainfall, and other water influences. Blackwater is always getting more organic input into the system. This tends to buffer the system more.

Could I conclude from this that doing water changes with peat filtered RO water with similar conductivities and pH as the tank's water would provide me with enough stability?

Another thing that I don't understand is that when I filter my RO water with peat, usually the conductivity goes up. I used to attribute this to the release of tannins. However, when I see the pictures that TomC makes on his expeditions, that water is usually tea-colored (I would guess rich in tannins) but then conductivity is often below 20 microS/cm.

For every answer there's two more questions...

 

[gerald]

I've been pondering that question for years too, having killed a few fish by not noticing when pH dropped to low 4's or less. A common complaint I hear about acidic phosphate buffers is that in order to have any appreciable buffering capacity it requires a fairly high concentration of buffer salts and the resulting TDS or conductivity ends up higher than optimal for obligate blackwater fish. But I've yet to hear any explanation of why conductivity itself - regardless of what salt ions are contributing to it - is a problem. If your sulfate buffer works well with very low total dissolved salts, you may be on to something useful.

My usual practice for blackwater fish is tap water mixed with rainwater (my tap water here is soft anyway, about 2 dGH and 100 uS conductivity), bunch of pre-soaked tree leaves and/or twigs, and a 1/2 teasp or so of aragonite gravel (crushed coral) in a box filter to keep pH from plunging too far and too fast. I dont add the aragonite in new tanks until I start seeing pH getting down below 6, which can be a few weeks to a few months. I cannot claim a great success rate with blackwater fish, especially checkerboards and chocolate gouramis which I feel lucky if they live beyond 6 months.

BTW I'd say every fish-keeper is a scientist, whether you like that label or not, and regardless of schooling. We try things, we see what works and what doesn't , we try to understand what's happening, and we make adjustments. That's pretty much the essence of science.

Raymond - there's probably a little bit of mineral soil in your peat that's leaching some ions. The tannins, lignins, etc that make the brown color are large non-ionic molecules, so they dont affect conductivity.

 

[dw1305]

Hi all,
Some of this was covered in Dave Soares "ok" thread <http://www.apistogramma.com/forum/index.php?threads/ok.12048/>. Ted has experimented with raising conductivity to make pH readings more stable, and his comments are well worth reading. Looking back I think both Gerald and I have been down this particular pathway in quite a few different threads.

These two quotes sum up my complete dilemma, since if I want to try to keep extreme soft water/low pH species I wouldn't know how to meet both demands.

Just do what Mike suggests and don't worry too much about the pH readings. I think it is probably only with experience that you can judge when the pH gets too low and compromises biological filtration. I would start by buffering the water up to about 100 microS (you can almost certainly do this with tap water, you are really adding dKH (from the calcium carbonate in the tap water)), and then reduce the amount of tap water in the water changes to give you ~50 microS in the tank. I'd be surprised if this doesn't work.

This is pH swing bit from the "ok" thread:

If you can visualise the acidity/alkalinity in terms of the relative amounts of proton (H+ ion) donors and acceptors, and their reserves, rather than being entirely reliant on their ratio (which we measure as pH) it becomes a lot easier. If you have small potential reserve of H+ acceptors and donors, (the soft water/low conductivity scenario), the pH can swing about over almost the entire pH scale, but there can only ever be a very limited change in the numbers of ions and it is the total amount of ions that is much more important than their relative ratio.

You get the exact reverse of this is in very strongly buffered alkaline water (with a huge reserve of H+ acceptors) where you need to make extremely large changes in water chemistry to effect the pH.

Electric eels original sodium bisulphate thread is here: <http://www.apistogramma.com/forum/index.php?threads/sodium-bisulfate.8399/#post-47057> and this contains a bit about buffering.

You can keep the pH of "water" stable at nearly any pH value, in biological work for this range of pH values
you would usually use either sodium citrate/citric acid or disodium/sodium phosphate buffers, but as Gerald suggests you need an excess of buffer so that conductivity will rise.

This is a citric acid buffer calculator, <http://www.egr.msu.edu/scb-group/tools/citric/cit.htm> and this is a phosphate buffer one <http://home.fuse.net/clymer/buffers/phos2.html>.

Another thing that I don't understand is that when I filter my RO water with peat, usually the conductivity goes up.

Weak acids also contribute to conductivity, so in this case it is the humic acid. You can substitute any salt and acid in this graph. (From the very useful "Conductivity - Introduction and Definition of Electrical Conductivity by Cole-Parmer"- <http://www.azom.com/article.aspx?ArticleID=5378>).

Normally this rise in conductivity would be hidden by the cation exchange of the sphagnum cells (where any other cation (Ca++, K+ etc) is exchanged for an H+ ion), but in this case some of the exchange sites in the peat may already be filled with a metal ion. This is quite likely in the more decomposed layers away from the actively growing ombrotrophic mire surface, or in peat from areas with polluted rain-fall. What you want is the very white peat from the upper layers of a Finnish peat bog, but this isn't environmentally sustainable.

cheers Darrel

 

[Mike Wise]

Mike, I keep my apisto's in 40 to 50 litres, usually in pairs or trio's and I do weekly 25% water changes. Would that qualify as relatively large tanks and regular water changes?

Personally, 40-50 l is a bit small for 2 fish. I usually use 20gal long tanks (~80 l) and suggest that you change 25% 2x/week if the water is below pH5. To tell the truth, I've been keeping blackwater species for so long that I can tell when the water starts to become too acidic and needs a water change by the appearance of the water and the behavior/appearance of the fish. Personally, for most species, I think you are trying to be too precise.

 

[raymond82]

Personally, 40-50 l is a bit small for 2 fish. I usually use 20gal long tanks (~80 l) and suggest that you change 25% 2x/week if the water is below pH5

I use 60*40*25 cm aquariums, which makes floor space comparable but of course the volume of water is less. I cannot easily replace my aquariums but I will try to increase water changes, especially when I'll have low pH water.

Looking back I think both Gerald and I have been down this particular pathway in quite a few different threads.

I'm aware of this and would like to apologize for raising a similar issue again. Most information is available on this forum (and e.g. the BCA forum), to me it's just difficult to remember where I read what. It would be great if all this information could be combined in a wiki-like page on soft water and pH. If I find time maybe I could combine all the information, for sure it will teach me a lot!

Thanks for pointing me to the part about the pH swings, I fully understand now (I think). I know the phosphate buffers (I actually work with them regularly) and I will do some experiments with buffering and pH. We have some commercially available buffers, in view of what Ted says about buffering pH and increasing TDS and fish still breeding I think it's interesting to try. It's also interesting what he says about the order of importance of KH, pH and conductivity, it surprised me to be honest.

In the end, I guess the bottom line is that I should just try. Soon as I'll be able to keep species that require more acidic water, I'll use peat filtered RO water. I'll just monitor the fish and the pH closely in the beginning and learn from the experience!

 

[Mike Wise]

I use 60*40*25 cm aquariums, which makes floor space comparable but of course the volume of water is less.

I think the confusion is equating territorial requirements with acceptable volume needs. For many fish, your tanks can work with no modifications in water change schedules. More sensitive species will need more care. In this respect, "the solution to pollution is delusion" is valid. More water/fish means lower pollution/volume.

 

[raymond82]

Thanks Mike, I'll keep that in mind. I'm looking forward to trying to keep more demanding species and gain experience with them. It will probably involve some trial and error but it will be interesting for sure!

 

[electric eel]

thanks again darrel!as i told you i never kept a log but i guess in a way i did(on the forum)i would have never thought to look back at the old threads.i saw today that seachem does make an acid buffer for ph between 5 and 7(i believe) but i am sure it would be expensive to use even if it was suitable for raymonds application.if i used water at 5.3 ph it must have dropped some because i specifically remember checking it after my dicrosus spawned and it was 4.7.i have every intention of doing some softwater fish again so i may want to revisit how exactly i did it. mike helweg had some fish on his list earlier in the summer that need soft low ph water that i have wanted to try for a really long time(apistagramoides pucalpaensis and licorice gouramis) but i excercised self restraint for once and decided to wait until i got in a better position to meet their water needs.i would be interested in the results of your experiments with buffers Raymond

 

[tjudy]

I have recently figured out that pH can be manipulated at the 'microhabitat' level for spawning fish. The reason some species need very low pH has more to do with the low pH's antiseptic effect on eggs than with anything to do with the health of the parents. Sperm motility is PROBABLY more closely linked with hardness and temperature than pH, but soft water is the easy part... use an RO machine.

I have been using long-fiber sphagnum moss stuffed into my spawning caves to create a lower pH environment where the eggs are being laid. Using a pin point pH meter I can pull out the cave with water in it and measure the pH, which is usually 1 - 2 points lower than the pH in the water outside the cave. I have Parananochromis gabonicus breeding in an aquarium with a pH of 6.5 - 7.0 (using RO water), but the pH in the caves with moss is pH 5.0 - 6.0.

 

[raymond82]

Wow, that's a really interesting method! It's for sure something I wouldn't expect, to see the pH lower in inside the cave compared to the rest of the tank. I'll make sure to try that once too, I actually have a lot of unused sphagnum moss. It's good to have a number of options, I'm gonna start with peat filtered RO water but it's good to have some more alternatives.

 

[gerald]

Weird - I would not have expected that either. But I guess it's consistent with Darrel's concept that in very low-conductivity water it takes very little change in the amounts of H+ "donors" and "acceptors" to cause what looks like (to a meter) a big pH shift. (Am I starting to grasp this now, Darrel?)

One other thing I've noticed is that my meter can give quite different readings used IN the tank versus in a cup of water taken OUT of the tank. I guess electric fields from lights and pumps may be affecting it. So now I always scoop water out to test it.

quote="tjudy, post: 69907, member: 194"] Using a pin point pH meter I can pull out the cave with water in it and measure the pH, which is usually 1 - 2 points lower than the pH in the water outside the cave. I have Parananochromis gabonicus breeding in an aquarium with a pH of 6.5 - 7.0 (using RO water), but the pH in the caves with moss is pH 5.0 - 6.0.[/quote]

 

[tjudy]

I assume that the reason the pH inside the spawning cave stays lower is that the concentration of hydrogen ions builds up in the enclosed space and relatively few escape through the opening. There is little water flow through an enclosed cave.

 

[dw1305]

Hi all,

I have recently figured out that pH can be manipulated at the 'microhabitat' level for spawning fish. The reason some species need very low pH has more to do with the low pH's antiseptic effect on eggs than with anything to do with the health of the parents....I have been using long-fiber sphagnum moss stuffed into my spawning caves to create a lower pH environment where the eggs are being laid. Using a pin point pH meter I can pull out the cave with water in it and measure the pH, which is usually 1 - 2 points lower than the pH in the water outside the cave.

Ted you are a genius, I can't imagine why I didn't think of this.

But I guess it's consistent with Darrel's concept that in very low-conductivity water it takes very little change in the amounts of H+ "donors" and "acceptors" to cause what looks like (to a meter) a big pH shift. (Am I starting to grasp this now, Darrel?)

Yes, I think the mode of action is the one that you and Ted suggest, and that some of the anti-microbial properties of Sphagnum (from the pectin like compound "sphagnan) may be relevant, as well as lower pH.
http://www.ncbi.nlm.nih.gov/pubmed/19187129

Antibacterial activity of sphagnan was assessed and compared to that of three other acids. Sphagnan in its acid form was able to inhibit growth of various food poisoning and spoilage bacteria on low-buffering solid growth medium, whereas sphagnan in its sodium form at neutral pH had no antibacterial activity. At similar acidic pH, sphagnan had comparable antibacterial activity to that of hydrochloric acid and a control rhamnogalacturonan pectin in its acid form........Sphagnan in its acid form is a weak macromolecular acid that can inhibit bacterial growth by lowering the pH of environments with a low buffering capacity.

The same factors may well come into play in the interstices between leaves, if we have leaf litter of Terminalia or Oak leaves.

cheers Darrel