Ph 6.0!

[Ulan]

Guppygal's problem is that her tank is too acidic, not too basic (the initial pH in her tank was below the pKa). This means she won't produce carbonate with baking soda, but sodium chloride and CO2.

Of course, you are right and the soda buffers the system, and its pKa is spot on. But the specific question was how long soda will stabilize the system, and my answer was: Not too long, if you don't add secondary, non-volatile buffers, keep the soda in solution by CO2 injection, or both. This would also prevent pH swings. Adding soda to a non-buffered acidic system will immediately rise the pH considerably.

 

[guppygal]

Guppygal's problem is that her tank is too acidic, not too basic (the initial pH in her tank was below the pKa). This means she won't produce carbonate with baking soda, but sodium chloride and CO2.

Of course, you are right and the soda buffers the system, and its pKa is spot on. But the specific question was how long soda will stabilize the system, and my answer was: Not too long, if you don't add secondary, non-volatile buffers, keep the soda in solution by CO2 injection, or both. This would also prevent pH swings. Adding soda to a non-buffered acidic system will immediately rise the pH considerably.

Ok - what should I do, to keep everything stable? Is the coral the simple answer?

 

[Ulan]

Ok - what should I do, to keep everything stable? Is the coral the simple answer?

Sounds like a good solution to me. Coral doesn't really add much of a non-volatile buffer, but it leaks soda on a constant and slow basis, because your acidic water will produce soda from the carbonate in the corals. Ideally, you will get an equilibrium between the soda production from crushed corals and the loss of CO2 from your tank. If your pH rises, the corals will leak less soda, if it falls, they will produce more. Just be cautious in the very moment you add something for the first time. You don't want to have a quick jump in your pH.

I'm not sure at which pH you will end up, though. I don't have any practical experience with fish or corals. Somebody else should chime in on this. I just grow blue green algae at work and use bicarbonate, phosphate and CO2 as buffering system. Which means I know a little bit of that side of the coin .