I have a system that I built that is having major leaking problems. I fixed it once and it recently started leaking again, so I think that I need to go with a whole new way of getting the water from the fish tanks to the grow beds...

Currently the IBCs have holes cut into the sides near the top and a PVC fitting is screwed on so that there is a rubber seal between the plastic of the IBC and the fitting. Then I put a water proof "putty" cement around the outside to seal it even further. This is not working at all. The seal breaks and every time the system turns on there is a major leaking problem.

The FT are propped up on wooden structures so that the bottom of the FT are level with the top of the GB and the GB and FT are about 2 feet away from each other. I currently have a pump in a sump tank in the ground that pumps water into the FT, which then gravity drains through the PVC piping to the GB (which eventually gravity drain back to the ST).

Does anyone have any ideas on how I can change the system to fill the grow beds? I am trying to stay with only one pump in the ST and gravity drain the rest. Can I go out of the top of the IBCs somehow and not have to worry about putting holes in the side of them? Is there a better way to seal?