My well water is 7.8 after sitting for 24 hours. I'm waiting to put my 20 clowns in the new 210 to see what I can do to lower the pH. My options are to have a 125g water holding tank for RO water to do water changes, have a drip system straight from the RO, or wait and see if the wood will drop the pH enough.
I've heard that there are aquatic plants like Vallisnaria that will bind calcium and or reduce pH by using the minerals and salts from the water.
This may be helpful for you spiff if anyone can confirm or provide sources for more information.