Help me please,

I have a DWC setup but i have a Ph problem. when my water comes out of the tap its 5.4-5.7, but when its im my steup itll raise up to 6.5 or so in 2-4 hours. this is wierd because water i set out for that long in a cup was still the same ph(maybe .1 or so off)

so my questions are; Can Oxygen via bubble stone raise your Ph by oxygenationg the water? Does anyone have ony Suggestions on helping me maintain a set ph without much adjusting? any advice is really appreciated