I think peat could be added to bring down Ph, and would work in say a bucket with water trickling through it, and draining out the bottom, but trying to use it as an actual filter media is just a bad idea. Too unstable, will degrade, and break apart, and become a maintenance nightmare. Maybe fill a 55 with it and very slowly trickle water through. Plan on changing it often. Again it is just a bad idea. Use muriatic acid to lower the Ph instead
