For starters, are you planning to drill your tank to do the closed loop or will you prefer not to, and have everything plumbed over the tank?
I imagine the closed loop will be fed by a direct flow from the tank using a 1-1.5" hose? Then the pump shoots it back into the tank via the OM at high velocity? Would I need to have one or two more 1-1.5" holes drilled in the tank specifically for CL drain purposes? Thanks again, your awsome! Eli
Ok...The plumbing size for the closed loop will all depend mainly on the plumbing size of the pump. Also, sometimes you may have to factor in how many bends there will be to get from the tank to the pump. If there are a lot of bends in the plumbing which can cause a bit of friction/resistance in there, sometimes you'd want to go up a 1/2 plumbing size or so to compensate for it. Also, some people will use multiple bulkheads for the suction/drain line for the closed loop pump. The reason why is not very many people want to plumb their closed loop using 1.5-2 inch plumbing...Get's too bulky. Also, just imagine how strong the suction would be at a single bulkhead on say a mag3600. That would suck in any small fish passing
So some people will use 2 or 3 bulkheads that all drain into one into the pump which means you can go with a smaller plumbing size (seeing you will be using a few smaller sizes that are equivelant to the single big one) and also, each drain point in the tank won't have a very strong suction so if a fish or snail happens to bump up into it, they can easily release themselves. Did I lose you?
Here are a few threads you browse through to see how some tanks were plumbed.
http://www.reeffrontiers.com/forums/showthread.php?t=5191 (This one Todd uses an OM for his closed loop! Really nice!!)
http://www.reeffrontiers.com/forums/showthread.php?t=2062
http://www.reeffrontiers.com/forums/showthread.php?t=14793
http://www.reeffrontiers.com/forums/showthread.php?t=4743
And I'll just post up a few pics of how I did mine on my old 38gal instead of making you dig through that thread(LOL) Also, if you don't want to drill the tank, let me know and I'll show you a few ways to do a closed loop over the top of the tank
K...I re-did my closed loop a few times so I'll explain what I did in each attachment.
Attachment 1: This was one of the first closed loops I did on this tank with (1) 1506 gph pump. The red arrow points to the suction/drain for the pump and as you can see I'm using two bulkheads that join into one so my fish wouldn't get stuck like I mentioned above from the suction being too strong. The blue arrow points to the return for the tank that, as you can see, go to 4different outputs.
Attachment 2 : This shows the other side of the plumbing inside the tank with the red arrows pointing to the 2 suctions/drains and the blue arrow pointing to the 4 outputs.
Attachment 3: The flow wasn't strong enough so I figured I'd add in another 1506 gph pump so I re-plumbed a bit. I didn't want to re-plimb the whole thing so I ended up using a single suction for each pump (as you can see they are now seperated, not joined and one goes to each pump). Then the outputs were split as well with one pump feeding the top and bottom left outputs and the other pump feeding the top and bottom right outputs.
HTH