for some reason the water in my tank has lowered to 7.0 while my tap water is 7.6. about 4 months ago i changed the substrate because i found out that my old substrate was coral sand that was increasing my PH.
Ive noticed now that the past few months my PH has dropped from 7.6, and at this moment of time its 7.0 which is annoying because my tap water is higher and i think its stressing the fish doing water changes.

Amonia: 0
Nitrite: 0
nitrate: 10
i know the PH would drop a bit because i no longer have coral sand but what could be causing it to lower from my tap water??

thanks Corey

oh and btw i dont have bogwood or dose with Co2...i only use fertilizers like i always have on this tank.

tap water quite often has an artificially high PH caused by the chlorine and other stuff added to the water. Once it has been aerated for a few hours it often drops.
Also if it has a low carbonate hardness (KH) or general hardness (GH) then it will drop rapidly when exposed to fish food & waste in the tank. The more fish in the tank and the more food being fed produces more nitric acid for the filter bacteria. The more nitric acid there is, the faster the PH will drop.

yeah that is true, i had the same problem also so i started using rainwater