Next your ph shouldn't be rising that fast. Which means your municipal water isn't clean enough, algae, or you have a light leak. I would address them all honestly. Feel the side walls of the system and see if anything feels slippery. If so algae is present and enjoy cleaning out your reservoir and buckets. If not go and get some black plastic sheeting and drape it over your buckets. This is normally a problem for people that use normal containers in their system like Wal-Mart totes and it shouldn't be a problem for you since yours are specialized but the fix is so simple and it will help rule out a potential cause of your problem. I'm thinking light could be seeping in through your clay pellets allowing things to grow in your water. Next filter your water or filter it better then allow it to sit for a day or so before you mix your nutrients. Allowing it to sit will give some of the dissolve gasses a chance to evaporate off ( like chlorine) you'll see small bubbles in it when the process starts. Then increase your ph to 6.0, increase your day temps to 78-80 and your nigh temps to 72-74, and increase your nutes to 1/2 strength. That should correct any ph,nutrient def, temp, algae/ bacterium,or hard water issues .