hey guys i'm running a flow and drain type of set up. My issues is that the ph lvls are off after 24 hours. I set it at 5.8-6.0 then 24 hours later it drops down to 4.9-5.3. the water temp is 76 (no cooler yet) water doesnt look milky or smell funny either, and the plants are still growing strong. What can be the issue? I just dumped the water 2 days ago.