Sounds like you're battling with the buffers in your tap water. Switch to RO or stop worrying about it. (You are still in range, alot of nutrient lines advise not to adjust the ph if its in between 5.5-6.5 )
ok but I've had the same tap water in my house for 7 years, ph out of faucet 7.4/160 ppm... Whats the easiest way to add RO water system to my basement sink? ... i would do a whole house RO water, but I heard its not healthy to drink bc of low ph???