It seems that the plant in the canister closest to the bottom of the picture is starting to shrink in size again. We tested the pH and it was a bit high. We mixed a new batch of nutrient solution and replaced it. It also seems that the caulk that we used to seal the canister is starting to rot through. We haven’t thought of a fix to this problem yet. perhaps the caulk disintegration is the cause of the high pH level.