Low PH in 8 year old tank?
Hello, I have a 90 gallon planted tank that has been running for about 8 years with zero problems up until about 8 months ago. Tank has a a medium load of low/medium light plants, about 8 Rainbow's, 6 Torpedo Barbs, Rupper Lip Pleco(aka Joe Pleco after Joe Flacco the Ravens QB) Brushmouth Pleco, Flying Fox2 and a Pinktail Chalceus(he's awesome and no aggressive at all) ehiem canister filters, Fluorite substrate and a big piece of driftwood, pressurized co2 system and PH monitor. I have not added anything in about 2 years. Prior to the last 8 months my co2 would run throughout the day and keep PH at 6.5 but over last 8 months it never runs and PH sits around 5.8-6.0. After a 50% water change the PH will go up to around 6.8 but by the next day it's back down again. I just tested parameters for ammonia, nitrites and nitrates and all are zero liked I expected.
Just can't figure out why after 7 years it decided to change and continue to have low PH reading. If it's nothing to worry about then great just wanted to see what the experts have to say.
I just recently started to get back into enjoying the tank, for awhile I was ready to sell it but could not bring myself to let it go. I've had a few of the fish the entire time and could not bring myself to give them away and have someone kill them for some stupid reason. Now I'm back at it and ready to add more plants and enjoy looking at the tank.
Any input would be great.