ph problem too low. cant get it up

[Aquattro]

Yes, a tank cycle will lower pH. The acids building up will cause this. And if it's at 7.3, I'd check your meter. At that level, the rocks will start dissolving
Once cycled, your tank will go thru a pH cycle everyday, due to photosynthesis of the organisms kept. This is both normal and ok. My favorite story of solving pH problems was to throw my meter away. Never had another issue.