Carbonates in water

[tjudy]

Here is a water chemistry question that I am dragging over from the Other South American forum.

I think that we cleared up the EC vs TDS debate. :?: What really is the effect of carbonates on 'soft water' fish?

What carbonates do is make it really hard to lower the pH. They are alkaline buffers. They soak up free hydrogen ions. So one obvious answer is that if the calcium carbonate level is high, the pH cannot be lowered to where we want it to be.

HOWEVER, does the carbonate in the water itself have a detrimental effect on the fish? If you could get the pH down (and keep it down), would high carbonates hurt fish if the TDS/EC of the water is still very low?

Here is the application I am aiming towards. One problem associated with soft water and injected CO2 is the possibility of a pH crash. Could calcium carbonate or sodium bicarbonate be used in small amounts to buffer the aquarium water just a little bit so that a crash is unlikely to occur? :?

Inquiring minds want to know....

 

[Cichlids1]

I've heard many plant people dose regularly with baking soda to buffer a bit and avoid the pH crash. I like living on the edge, not sure of the fishes opinion tho, and do enough waterchanges that it doesn't seem to be an issue (Knock on Wood!). I get some swings from time to time that are a bit stressful, but I have yet to have one bottom out and stay there. I wish I could find a magic formula that I can set the pH at 5.0 and it stays there until I want it to move

 

[tjudy]

If you want a magic mix that will stay at 5.0 pH, there is a way to do it. You basically have to reconstitute from R/O, unless you have a very accurate number on the carbonate level in your tap water.

Seachem sells two products: Alkalinity Buffer and Acid Buffer. They include a chart on the side of the bottles of how much of each to use to keep the pH at a specific level. I have not personally done this, but I have made similar solutions in lab to use as calibration stock solutions. It should work, but the variable environment of an aquarium will always create some fluxuation.