I'm new to the hobby and think I might have made a rookie mistake by purchasing low pH soil (tailored to CRS) for my 1ft nano cube. It's Japanese made if I'm not wrong (H.E.L.P Advanced Soil for shrimp), and it's supposed to keep the water at pH 5.5. Obviously some kind of organic acid inherent in the soil accomplishes this. The problem is the acidic environment prevents the existence of carbonates by acid/base reaction; the soil manufacturer claims 2 kH, but I'm doubtful. It's probably zero atm, after 2.5 weeks. pH is off the charts on my strip tester, so <6.2 for sure. from the color, I'd guess it's much lower.
My main desire is to grow hemianthus cuba. But I do intend to keep shrimp eventually, and a light fish load so I want to be careful and not gas the creatures. I'm using pressurised CO2 (with a ceramic mister, not ADA type pollen diffuser), which means I also have to worry about pH fluctuations in a tank with no buffering capacity. I have a drop checker but currently waiting for a precision weighing scale in the mail, so I can make a 4dkH solution. I'd like to hear if anyone has experience with high tech tanks with acidic soil.
I've heard about crushed coral, but don't fancy the GH boost. Also, approx 20% of the tank is soil. It will probably take a hunk of coral to neutralise all the acids and would defeat the purpose of using this soil. I'm less than a month into this tank, and might consider tearing it up to replace with more neutral substrate like powersand and/or aquasoil. But I'd break my back replanting all those cubas. Thoughts?