I put together the filters today, two 3" bulkheads to Join Barrel A to Barrel B and two 2" bulkheads to drain Barrel A and Barrel B. I still have to put the 3" inflow bulkhead in Barrel A. When I first started filling, only the 2"bulkhead in barrel A leaked, then the 2 3" bulkheads started to drip. I suspect the weight of the water in the barrels put some pressure on the 3" bulkheads. The 3" bulkheads almost stopped leaking, but the one 2" bulkhead has a steady stream. I think I'll disassemble the 2" bulkhead, as there almost seems to be a physical defect (trapped plastic or cracked gasket), but what's the best overall approach? Silicon on the Flange/Gasket side or Silicon on the outside? All the bulkheads are nut in. The 2" bulkheads probably need tightened a bit more, but the nuts are a little thin.

> I just found out about Uniseals and they have some appeal for joining > a radiused surface with a tube. The hole is cut with a hole saw, > which helps to keep the hole round, or to the shape of what is going > into the hole. I haven't tried them yet, but I have a couple 4" > waiting to be put into service. > > http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/8600 I have always wondered why everyone here complains about the prices of Bulkheads, until now - I followed the link above to them and couldn't believe a 3" bulkhead (equivalent to what I use) listed at $70. At a farm equipment dealer & supply depot in Canada, that bulkhead is $12. They use them on the big plastic tanks that hold hundreds to thousands of gallons, to haul water, liquid fertilizer and weed chemicals. Is it the fact that it is listed for 'recreational pond use' ? If they were that expensive, I would also be looking at Uniseals Gale :~)