leaking

From my previous thread https://www.rollitup.org/t/rdwc-waterfall-design-critique.978555/, I purchased the HDX totes, 2" bulkhead slip x slip and PVC supplies. Now, I'm dealing with leaking issues. I have tried to apply flex seal glue on the inside of the buckets twice and it still leaks...

Hey y'all newb here needing advice on leaks if possible. I have a 12 bucket bubbleponics rdwc which I've set up but 4 out of 12 buckets have a minor leak......I'm trying to figure out a way to seal them properly. I bought the hydroponic system the way it is with all the parts so I didn't think...

Doesn't say anything on the bottle regarding aquarium use. I've noticed my bulkheads leaking on the inner side (where the pipe is inserted) as well as from the outer rim of the bulkhead so I've turned to silicon sealant. What do you guys think? Anyone have experience using this in hydro...