bulkhead (?)

I do not use silicone caulk. Instead I use plumbers grease (Silicone or Telfon based) or Leslie’s Pool Lube. Any one of these works great…Leslie’s is the best buy…I think about 6.50 for a tube that will last a lifetime. I actually use this stuff on all my rubber parts. Great stuff!
 
I've always just snugged them tight. I haven't had any that leaked, but I can see how silicone or another sealant would be a little extra insurance against it.
 
I think I'll try to find some of that "plumber's grease" sounds like something good to use on threads for sealing rather than tape.
 
I think I'll try to find some of that "plumber's grease" sounds like something good to use on threads for sealing rather than tape.

Greg, it actually would not seal threads. Your choice there is either telfon tape or plumbers dope. They now make that stuff for plastic threads as well, but I'll still stick with teflon tape for my aquarium. I have no idea what's in plumber's dope, and don't care to find out by having some of my stuff die.

Plumber's grease (or Leslie's Pool Lube) lubricates and protects rubber stuff without causing it to swell (like petroluem based products would). The stuff I treat with this stuff lasts forever. With my canister filters for my freshwater tanks, if I've bought the filter new, I've never had to replace gaskets.
 
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