sakura - i did a search for mopani on applesnail.net and yeah, its most likely the mopani that is lowering the PH too much. Bummer as I liked my chunk 'o wood. I have no idea what the PH is -don't have a test for it.
Snails will certainly suck the calcium right out of the water, but not enough to affect the pH, IMPO. Crushed coral used in the filter or substrate helps, as does Texas holy (hole-y) rock (basically a limestone/coral rock), and crushed oyster shell (used as chicken grit--but very sharp so I'd put it in the filter) and even clean sea shells. The wood is one thing bringing down your pH. You can remove it or add other things like the above to keep the pH steady. Ammonia from waste will bring down the pH too, so keep up with the water changes. And of course your tank is SERIOUSLY overstocked.
I have some small peices of coral and seashells...Wonder if its enough to make a difference. Do bettas and the soon to be here plecos like higher or lower PH? I also have some IAL on the way...probably ont be here for like 2 weeks though.
Should I take out the wood and replace it with:
My anubias need someplace to live...
I don't really need the mopani since I bid on some cholla wood on AB
I DONT WANNA WORK TOMORROW..ITS SO BORING with like 2 customers a night