I currently have a PH of 6.0 in my 55 gallon tank and I need a ph of 7-7.5 or somewhere near there. I use to have a PH of 7.5 a couple weeks ago but for some reason my PH has dropped to 6.0 and I have plenty of aeration too. I added CO2 a little while back and I believe thats what caused the drop so I removed it to see if it will go back up. How long will it take for the PH to go back up if I have good aeration? My Tap water PH is 7.5.