pH swings with Aquasoil? - The Planted Tank Forum
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post #1 of 6 (permalink) Old 10-30-2012, 03:34 AM Thread Starter
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pH swings with Aquasoil?

I have been told that Aquasoil by ADA is a very good substrate. I saw that it lowers pH, though, and so I am wondering: Wouldn't that create pH swing in my tank if I put in water with a pH of 8 during a water change? Wouldn't the new water raise the pH only to be lowered again by the aquasoil? It does sound like a good substrate, but I wouldn't want to hurt my fish by getting something like that.
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post #2 of 6 (permalink) Old 10-30-2012, 04:26 AM
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Yes, a pH swing would most likely occur. Although most hardy fish probably would be ok, I am planning on getting the substrate to keep the pH at 6.5, which is what distilled water usually is. If you can lower the new water BEFORE it enters the tank that would be your best bet.

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post #3 of 6 (permalink) Old 10-30-2012, 05:02 AM
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ADA Aquasoil Amazonia is widely accepted as a very good substrate for plants and fish. It is used by a very large number of people, who are happy with it. Those people don't concern themselves with pH changes during water changes. Fish experience pH changes in nature, when it rains, so they obviously aren't bothered by them. Changing 50% of the water in a tank, using tap water for the replacement, will almost always cause a pH change, but fish clearly are invigorated by that. Using CO2 during the day, and shutting it off at night introduces big pH changes twice a day, and no one reports problems with fish as a result. So, I believe pH changes are not a problem any time. But, fast KH changes definitely are a problem for fish.

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post #4 of 6 (permalink) Old 10-30-2012, 07:05 PM Thread Starter
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So, shrimp such as RCS and CRS would be OK with pH swings created by the aquasoil?
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post #5 of 6 (permalink) Old 10-30-2012, 07:50 PM
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Originally Posted by bud29 View Post
So, shrimp such as RCS and CRS would be OK with pH swings created by the aquasoil?
No, shrimp are more sensitive to changes and thus prefer stability. I don't know what kind of "swing" you are referring to, but for CRS most people use RO water, which has a lower pH and should not change the tank pH too much.

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post #6 of 6 (permalink) Old 10-31-2012, 11:36 PM
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Test the mineral and other levels in the tap water.

Most livestock do not care what the pH is doing, as long as it is within their preferred range, but the levels of the things measured by those tests need to stay as stable as possible.

Adding CO2, for example, is not changing any of those mineral levels, except, maybe KH, just a bit through the interaction of CO2 and carbonates. So small hobby test kits are not likely to pick it up,
Fish are just fine with the CO2 induced pH changes.

Aquasoil removes the KH from the water, allowing the pH to drop.
When you do a water change with water that has more than just a trace of carbonates, that is creating quite a change in the KH level in the tank. This can cause some issues.
Here are some solutions:
a) Add something to the tank mid week (more or less) that will maintain the KH at whatever level is optimum for the livestock and plants. Potassium bicarbonate, baking soda or other materials. This way, when you do a water change yes, the KH will be changed, but it will not be so extreme.
b) Use new water that is close enough to the tank water for GH, KH and TDS that there will not be more than about 10%-15% rise in these values. Most fish can handle that just fine. (I do not know how much shrimp can handle). Depending on what is making the pH so high in your tap water, you might have to use reverse osmosis water then add back just the minerals you want. Then monitor the tank through the week and add minerals as needed. That substrate is high CEC, and will remove minerals from the water, as you are noting with the carbonates.
c) Do more frequent water changes that will keep adding KH from the tap to the tank on a more steady basis.
d) Top off with tap water. This will also be adding other minerals, but the plants might be using them up, or they might not.
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