I recently just started up a pond style shallow tank to house a male betta and a small shoal of pygmy cories. The tank has been running for about 11 days now, and it's been going well (I instant cycled it with media I pre-seeded). It's about 3/4 way filled so I'd estimate about 4 gallons of water volume. I used an entire 3lb bag of UNS contrasoil to build up the emersed slope, and previously thought it was the one aquasoil that doesn't lower pH. Apparently it WILL buffer pH to around 6.8 over time. Now, my tap comes out at 7.0 and hits 6.8 after it gasses out. However, in this tank which started at a 6.8, dropped to 6.6 after the first 5 days and is now a 6.4. I did use rocks I found in my local stream but did a cider vinegar test and none of them fizzed so I assumed they would be fine. I'm not sure if it is the contrasoil or the river rocks lowering my pH, but does anyone think this will be an issue for my betta and cories, and also for my beneficial bacteria? Also if anyone has any experience with the contrasoil long term, I would appreciate that too. Thanks!