Buffering RO water

maxw47

How should I go about buffering RO water? I get how to add the minerals and such back, but the buffering part is confusing me. I'd like to stick with seachem products. I think I would be using their neutral regulator, acid buffer, and alkaline buffer. All that I can tell from reading about them online is that you're supposed to add acid and alkaline buffer in order to get the desired pH, and neutral regulator to buffer that (up the KH) and keep it from shifting around. I am assuming that more specific instructions are on the product labels themselves. Am I right on this? As of now, I am only keeping lots of plants and breeding some platies, so I'm looking for a pH of 7-7.5 and a Kh of say 4-5 (sound right?) Would I just add some alkaline buffer to get to a pH of 7.5, or nothing for a pH of 7. And then add a certain amount of neutral regulator to get me to my KH of 4-5? Please put in what you know and thanks for any advice!

Geomancer

Well, all their instructions are on their website, the bottles will not contain any extra info.

However, personally I wouldn't bother if you are going for hard water... I would just use a calcareous substrate like crushed coral.

Byron

I agree. Mixing varous chemical preparations can get troublesome, and very expensive. Knowing what fish you intend keeping would help us suggest better alternatives. Also, can you use some tap water mixed with the RO? What is the GH, KH and pH of the tap water?

Byron.

maxw47

We have a water softener that uses sodium. I guess the sodium ions aren't very good long term for the fish and plants. I only have platies right now and they seem to be able to handle it alright. The plants don't like it though. Even with a good substrate, decent lights, and co2, they grow slow and the tank gets algae. I had some panda cories that didn't do well too. I want to start keeping some more sensitive, soft water species too.
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Byron

I agree that softeners using sodium can be worse than the hard water for soft water fish. The livebearers are better able to tolerate salt, but as you say, plants may not.

My suggestion here would be to use a calcareous substrate in the tank with livebearers (only) and plants. Crushed coral and aragonite blend sands are ideal. Another member pointed out a glitch though, and that is during water changes. But here I would suggest you use water pre-softener, assume it is on the hard side? You might even manage with this without the special substrate. Livebearers need medium hard to hard water, with a basic (above 7) pH, and there are many plants that will thrive in this--Vallisneria for one.

For the soft water aquarium, use RO water and add Equilibrium (a Seachem product) to raise the GH sufficient for the plants. Soft water fish do not need any of this, but they will be fine. I have near-zero GH and KH tap water, and only for my plants do I use Equilibrium to raise the GH to around 5 or 6 dGH. The pH will remain acidic. With regular water changes, there should be no issues. I never mess with KH, as I have seen no pH problems.

Byron.

maxw47

Thank you so much! I found some info on seachem's acid buffer and alkaline buffer. Have you ever used these? I know that you said that you don't like to mess with the KH, but I think that I am going to use the acid and alkaline buffer to get a KH of 2-4 or so. I am going to have CO2 running on all of the tanks and I don't want a pH crash. Should I worry about that? I'd like to stick with the seachem products, and adding them to the RO water before water changes, only so that I know what my KH and pH will be, because I don't know how to regulate that if I had let's say crushed coral. Do you see what I mean? Again, thank you so much!

Byron

I need to know a lot more before I can comment beyond what I've already suggested. What is the GH, KH and pH of your tap water before it goes through the softener. You can get the GH and KH from the water supply folks, they may also know the pH. And I assume you would be able to obtain this water (pre-softener)?

A pH crash is highly unlikely in a planted tank with balanced fish load, weekly 50% partial water changes, and not overfeeding. In my 20 years of dealing with very soft water out of the tap, I have had tanks with the pH below 5, and tanks with the pH in the 6's. I only keep soft water fish, and this has never been a problem.

Byron.

maxw47

Here are the params before the water softener-
-pH: 8.2
-GH: 7
-KH: 11

This is all making more sense now. I was just nervous because I had heard stories and what not about peoples pH crashing after starting to add CO2, and it turned out their KH was really low. But their tanks were probably under different variables. All of my tanks (hopefully) are going to be very well planted and have a healthy amount of fish. But let's say that I sold all of the fish in a fry tank, or I transfered a lot of plants from one tank to another, leaving it lightly planted. At that point, would the tank be vulnerable to a pH crash? Has anything similar happened to you? I am not really that worried about this, but I just want to know. Thanks again for so much help!

Byron

Not likely, and no, to your last two questions. Let's see if I can explain a bit. First, the water parameters of the tap water, meaning GH, KH and pH, will tend to remain the same in an aquarium up to the point when biological actions occur, as will happen in any tank with fish. Organic waste increases, and the breakdown by bacteria creates CO2 which adds carbonic acid to the water, lowering the pH. The KH acts as a buffer, and the higher the KH the less pH will fall. This is very general. Other factors affect all this. The more substantial the water changes, the more stable things will be. Live plants will use CO2 and nutrients from the organics breakdown. Not overfeeding will keep the waste less. And so forth.

It is possible to have the pH lower so far that certain fish are affected. Our profiles give pH ranges for each species. Regular weekly 50% partial water changes in my experience prevent any serious problems with this.

To your water params, the GH at 7 dGH [presumably this is degrees] is good. The pH is high, and the KH at 11 dKH is likely to keep it there. As you now have and use RO, I would experiement with mixing pre-sopftener water with RO. Try half/half and see where the GH and pH fall. You might find this article helpful:
Water Hardness and pH in the Freshwater Aquarium

maxw47

I should have mentioned this to you earlier, but I don't really have access to the pre-softened water. I have tried all of the outside spigots and everything inside the house, and they are all connected to the softener. So I can't really mix the RO with it and get good stuff. All of this making more and more sense now. If these tanks were dirted (dirt substrate w/ gravel on top), would that effect the pH? Plus the CO2, my pH would probably be brought down significantly. You mentioned crushed coral, aragonite, etc earlier. Would you recommend having a filter bag (one of those fabric bags that filter media is held in) with like crushed coral in the filter or in the sponge filter bubbles. Do the buffering qualities of crushed coral change over time? Again, a tremendous thank you for your advice!