Strangely Drilled Used Tank (what to do?)

[SkinnyPete]

I just bought a used 125g tank which has dual overflows. Now, the previous owner plumbed a bulkhead through one of the overflows. So, there is a bulkhead in the bottom front of the overflow and glued plumbing which connects the bulkhead to the return bulkhead in the bottom of the overflow box. He told me he used this as a return from a closed loop. He had an intake over the top of the tank and used this odd bulkhead to connect a series of pvc pipes under his rocks as returns. Now, it seems like a fine idea but in case of power outages, you'd need to break the siphon somehow.

So, now I'm thinking use one overflow as normal, standpipe and return. use the other bulkhead's standpipe and return over the top of the tank. And use the bulkhead in the overflow as an INTAKE for a closed loop, except I could mount the pump on top of the tank, above the water level. I can return it using a series of spraybars at the top of the tank. If power fails, I'll have no problems with the tank draining because the pump will be above water level. Does this sound like it would work? Any other ideas on how to utilize this stupid hole in the overflow?

pics to follow...

 

[melosu58]

Moved to General Hardware and equipment discussion.

 

[SkinnyPete]

You know what? Stupid question. There is nowhere for water to back siphon, hence the name 'closed loop' so I think my question is irrelevant. There isn't really a need to break siphon.