ph level is too high

[Silencio]

I have 150 gallon tank and I had ph at 7 with water changes one time a week at 25 gallons. I've been changing 20 gallons everyday because I have purchased 5 small Discus fish and I've been feeding them 3 to 4 times a day for a week now. My water ph level has tested at 8 any suggestions would be much appreciated.

 

[poppalina]

Test the water from the tap to see if it reads the same as your tank, also did you add anything new to the tank,, rocks, sand, etc.

 

[David R]

Test your hardness.