CORRECTION: the PH of my solution in res is 5.5, my RO water is at 6.7... sorry for the confusion.

change solution every 2-3 weeks. They eat about 2 gallons every 4 days so i replenish with a 3/4 solution.

I run the heavy duty commericial air pumps so areation is no problem.

I have other buckets running the same nutrient solution and are the same size with no current problems. all of which are at 600-750ppm.

roots are in healthy condition, trust me I have seen some bad root rot before.