Hello! New aquarist here. I have a 5gal fluval spec, moderately planted with 1 betta, 5 rasbora, 5 shrimp, and many snails. I do a water change (~20%) every 7-10 days, and easy green and easy iron once weekly. My substrate is flourite black + rocks + sand. I'm finding my parameters are staying stable except my pH. My tap water pH is 7.8 and I'm trying to keep my tank around 7.0-7.2. I have drift wood and Indian almond leaves (and love the tannins!), but I keep finding that after a few days and a water change, the pH creeps up to almost 7.6!! I'm noticing some crypt rot as a consequence, I believe. I have pH down drops, but I would prefer a more sustainable way to keep my pH low. I think adding a buffer like crushed coral will help with the fluctuations, but I fear it will hold my pH around 7.4-7.6. Any other suggestions? Am I doing something wrong?
Ammonia 0
Phosphate 0
Nitrate <20
Nitrite 0
GH 75ppm
KH 100ppm
Sorry I only know KH/GH in ppm because I have strips