Can you run a closed loop from the internal overflow?

[KenT]

I recently set up a 180 and want to add a closed loop. The tank is glass and has 2 built in overflows. My return pump is an Iwaki 100 @ 11' head, and also T'd off to supply the chiller. My overflows are not maxed out.

I want to put the intakes for a closed loop into each of my overflows. I will be using a Blueline HD100. I will have to go over the top of the tank since I cannot drill the tank. Will the overflows, not the drain holes, be able to flow this amount of water? Approx. 2800 GPH.

Thanks

 

[GSerg2]

You will likely pick up too many bubbles with the intakes in your overflows. I tried a similar thing by dropping a Mag7 down into one of my megaflow overflows and I eventually gave it up because of the bubble issue and maintenance problems. Even with the pump all the way at the bottom, there were lots of micro bubbles.

I don't know what kind of overflows you have but if they are Megaflows, I think they are only rated for about 600gph each. So 2800gph will probably be way too much.

 

[r00onmac]

not to mention if power goes out to your return for whatever reason (GFI trip or something) and the closed loop keeps running.. itll run dry in like 20 seconds and then be destroyed

 

[sabodish]

i ran a closed loop this way for 3 years on my old 360 gallon. i did have a small microbubble problem also. i really dont think theres a way to prevent bubbles totally, but it wasnt bad enough for me to take it apart. i would check out melevsreef, he has step by step instructions for the over the top closed loop.

 

[D-Nak]

Here's my thought, let me know what you think of this.... I'm in the process of setting up an AGA 120 with the older overflows (the ones in the corners, not the MegaFlows) but I think the concept will be the same....

My plan is to use the 1" holes with Dursos, while using the 3/4" holes (designed to be used for the returns) for closed loop intakes. The Dursos would lead to my sump, then to a return pump and into two 3/4" SeaSwirls. Pretty much as standard set-up for this part.

Since the SeaSwirls need to hang on the tank, I have 2 extra holes in my overflow. Basically, what I plan to do is create PVC u-tubes and have them hang over the overflow into the tank (in the place where the return cut outs are, then add a strainer to the end (think HOB power filter). The bottom of the u-tube will be connected to a bulkhead through the 3/4" opening in the overflow.

The two 3/4" PVC outputs (one from each overflow) will be joined together with a tee which will lead to a pump and then the return will go into an OM squirt (haven't finalized this part yet) or some other sort of distribution device (could be a simple pvc pipe with holes in it and placed along the bottom of the tank).

Of course, I will have emergency siphon breaks in case there is a power outage and the closed loop leaks -- this will avoid draining the tank down to the bottom of the u-tubes. However, if leaks are avoided there shouldn't be any other problems during a power outage since the closed loop will always have water in it.

This isn't an original idea as I've seen someone else use a similar system, but I can't seem to find it on RC.

D-Nak

 

[D-Nak]

Oops... I just re-read your post... 2800gph is a lot for two 3/4" inputs. Why don't you just use U-tubes and go over the top of the tank? Then you can make them any size you want.

D-Nak