• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

RO Water, Remineralizers and pH

Thank you for explaining - no CO2 in this tank but I’m starting a new tank next week and I’ll be using it then. It will be interesting to see the difference!
 
Hi all,
It will be interesting to see the difference!
I'm not personally a CO2 user, but what should happen is that the pH should remain at the level that gives you a one unit pH drop (~30 ppm CO2) throughout the photoperiod, even though the water will be saturated with dissolved oxygen at the end of the photo-period.

You might be interested in <"Canford Park">, not exactly an aquarium, but an example of the effect of dissolved gases on pH.

cheers Darrel
 
Last edited:
Hi @Christel

Thank you for this clarification.

So, we ought to measure tank water pH every day at around midday, for example - regardless of whether or not we are injecting CO2. Would you agree with this and what range of pH values should we aim for?

JPC
Hi, I would aim for a pH between 6.4 and 7.2 in an aquarium with many fish. This fits with most fish and most aquarium plants. If you want to cultivate special plants, like some Eriocaulon species, you have to lower the pH even further - but that doesn't work with all fish. Such plants should be maintained in a special aquarium. We also have to consider the health of the fish in our aquarium.

In the beginning it makes sense to measure the pH in the morning, at noon and in the evening. In the evening it is higher because the plants have used CO2. I don't have a night cut-off, because in the morning the pH is not in the dangerous range for the fish. As soon as a stable environment has settled down, you don't need to measure the pH value so often. By the way, good plant growth can be seen in the assimilation of the plants! It is important to observe the plants well - at some point measuring is no longer important, but you can see the plants and the fish whether everything is good or you have to intervene. Christel
 
Hi all,
By the way, good plant growth can be seen in the assimilation of the plants! It is important to observe the plants well - at some point measuring is no longer important, but you can see the plants and the fish whether everything is good or you have to intervene.
That is the <"approach I recommend as well">. Put at its simplest level "the plants (or fish) can't lie".

It doesn't sounds as "scientific" as doing lots of water tests etc., but it is an entirely <"valid scientific method"> and really just <"a form of bioassay">. I'd like to be able to <"quantify exactly the processes"> that were occurring in the tank, but there are a lot of variables and "watch the plants" works.

cheers Darrel
 
Last edited:
I’m just starting with equilibrium to lower the ph but I’m wondering once the kh is 0 how do I stop the ph dropping too far? Will my tank provide natural buffers? I have some rocks in there. I have soft water fish - threadfins and chilli rasboras - but I don’t want to drop lower than 6. Thank you
 
Hi all,
once the kh is 0 how do I stop the ph dropping too far? Will my tank provide natural buffers? .......... but I don’t want to drop lower than 6.
The tank will buffer itself to some degree, but you don't need to <"worry about the pH dropping">.

The issue is <"with the pH scale">, rather than the water. Buffering and pH are conceptually difficult and most of what you read is based upon a premise that we know isn't true. Nitrification is compromised in soft water, but to nothing like the level that was assumed before we knew <"which microbes were actually involved in nitrification">.

One reason that "blackwater" fish are difficult to keep is that they have evolved in soft, acidic, tannin stained water where all microbial activity is much reduced. When you keep them at higher pH levels they often succumb to bacterial infections.

You can't <"extrapolate from hard water to soft water">, in hard water it takes big changes in water chemistry (ionic constitution) to cause small changes in pH and in soft water large changes in pH are caused by <"small changes in water chemistry">. The way I get around this is to ignore pH and just look at changes in water chemistry, via measurement of conductivity.

Even though I'm not a CO2 user, it was hearing about CO2 injection that made me interested in <"pH stability as a concept">. Once you know that aquascapers have healthy fish, but their tanks go through a cycle of a drop of one pH unit, and subsequently a rapid rise of one pH unit, every day you know that it isn't pH change, as such, that is the problem.

cheers Darrel
 
Thanks Darrel- this is really fascinating. I guess my main worry is once I remove kh the ph will swing all over the place. After everything you have shared I’m not worried about a unit of fluctuation anymore but I’d like to drop it down a level of fluctuation but no more than that. I will use equilibrium and observe what happens - I can always add the kh back in. Another plan could be to keep the kh at 1 and see what the botanicals do - maybe that’s a good mid way. Thanks again for your help. I’ll read your links.
 
Hi, I would aim for a pH between 6.4 and 7.2 in an aquarium with many fish. This fits with most fish and most aquarium plants. If you want to cultivate special plants, like some Eriocaulon species, you have to lower the pH even further - but that doesn't work with all fish.
Hi @Christel

Thanks very much for your reply, which is very helpful - particularly the pH figures immediately above. I tend to prefer the soft water, lower pH fish anyway - Cardinal Tetra, Rummy-Nose Tetra, German Blue Rams, Otocinclus, etc.

JPC
 
The idea of using seachem equilibrium with RO is that it targets gh and not kh. So with 0 kh the ph can drop. At least that’s what I understand from reading this thread and others. I did a w/c yesterday with RO with just seachem equilibrium and the ph has indeed dropped from 6.8 to 6.6 (just tested before lights on) and I’ll see what happens as the day goes on.
 
The idea of using seachem equilibrium with RO is that it targets gh and not kh. So with 0 kh the ph can drop. At least that’s what I understand from reading this thread and others. I did a w/c yesterday with RO with just seachem equilibrium and the ph has indeed dropped from 6.8 to 6.6 (just tested before lights on) and I’ll see what happens as the day goes on.
Yes supposed to be GH only.... but Interesting observation. Whats your tank KH ? With very low KH and specific tank conditions, I wonder if the pH would have dropped regardless of the equilibrium.
 
Last edited:
The kh has been at 2 for a while and the ph starts at 6.8 just before lights on then rises to 7.6 before lights out. With the 50% w/c yesterday with just equilibrium the kh is now 1ish and the ph dropped to 6.6 before lights on. At midday it was 6.8 so definitely lower. The gh has dropped to 3 which I didn’t mean to do - need to work out the right dose of equilibrium to keep it at 4. I think I’ll need to add botanicals to hit the 6.4 mark but we’ll see.
 
Once you know that aquascapers have healthy fish, but their tanks go through a cycle of a drop of one pH unit, and subsequently a rapid rise of one pH unit, every day you know that it isn't pH change, as such, that is the problem.
Hi Darrel (@dw1305) & Everyone

I think you will all find that the following study supports what is being said here in the preceding posts. And, note the date of the document below - almost exactly 17 years ago...


Although the above study was carried out on surface waters, I can see no reason why the findings of the study shouldn't apply to ornamental fish and other livestock in an aquarium setting. Please shout if you think otherwise!

JPC
 
Hi all,
I think you will all find that the following study supports what is being said here in the preceding posts.............Although the above study was carried out on surface waters, I can see no reason why the findings of the study shouldn't apply to ornamental fish and other livestock in an aquarium setting.
It does, pretty much, says the same thing and there isn't any reason why it shouldn't be equally applicable to both ponds and streams and aquariums.
..........The pH of lakes and streams often changes during the day in response to photosynthetic activity. In ponds having poorly buffered (low alkalinity) waters, the pH may fall to approximately 7 in the early morning and increase to 9 or more in the afternoon (Boyd 1990). Good fish production usually can be maintained in spite of these daily fluctuations. In most lakes and ponds, diurnal pH fluctuations during the summer, when photosynthetic activity peaks, are generally less than 2 pH units, while in streams are generally less (e.g., 0.5-1.0 units). Unless diurnal fluctuations result in ambient pH falling below 6 or being elevated above 9, they generally have no adverse impact on aquatic life. This is supported by the study findings discussed below...............
Reading through it I think it might not be entirely objective and they may have had an agenda, possibly to do with trying to deflect complaints about the acidification of certain water sheds?

cheers Darrel
 
Hi Folks,

Please refer to the study that I mentioned above in post #55.

Although the above study was carried out on surface waters, I can see no reason why the findings of the study shouldn't apply to ornamental fish and other livestock in an aquarium setting.

On reading the study again, I see that the aquarium setting and freshwater tropical fish do in fact get a mention on page 6 in the second paragraph.

JPC
 
Back
Top