So Im setting up my 21gal (80L) for two gouramis, some guppies and kuhli loaches. Everything is going good, I've acquired a good amount of plants, the tank is cycled, the only problem I'm having is my ph of 8. I want to get it down to 7.5 at least. My plan is it do just that with driftwood, catappa leaves and some peat moss. I'm suspecting my oversized filter agitating the water too much is the culprit for my ph spike. I've heard that adding organic compounds to lower ph is not a permanent solution though. So how long would it be before I'd have to replace the leaves & peat again?