12-26-2006, 08:59 PM
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Drill the hole so it points down in the tank...Simple enough.
I don't know anyone silly enough to run a suction tube for a wetdry to the bottom of their tank. If so, bully for them, they get what they deserve. Anyone using only a utube for suction is just asking for problems, check valve or no. There is no one way to make them equal out. Just spend the $50 for an overflow box. BTW, I never once mentioned in my reply that this was advice for an internal overflow. My advice was for a HOT overflow. If for any reason someone was to attempt using only a Utube for suction then it should be cut no more than 1" below the surface and or at least have a hole drilled in it near the surface so that when exposed it breaks the siphon. However, when the pump kicks back on, NOTHING will restart the suction and your sump will overfill your tank causing serious damage to surrounding areas.
Your other question, if a seal should fail in a built in overflow. I've had this happen. Just like anything else, when enough water leaks out it cannot overflow the teeth, thereby ending the troubles. However your sump will dry and you could eat your pump.
Check valves are not adised by myself in your basic wet/dry set up. they fail. To many people would bet the farm on them and anything could cause it not to close properly. Also good luck finding one that would not be a serious restriction in the assembly. I install 12" backflows weekly. I'm pretty familar with check valves. If you could find a PVC swing check that is gravity fed you might have a decent product but I haven't seen any good ones. Spring checks are the only "sure fire" check valve.
A properly set up system needs only a 3/32 hole drilled just below the water line to break a back siphon.