I second that. Flow through sumps should be kept to a minimum so you don't end up with a micro bubble problems later. That being said you may be able to reduce the size of your overflow pipe. I can't find it now but there was a thread on RC of a similar tank to what your planning.

Are you planning on drilling the bottom of your tank? I've seen at least 1 tank break due to that. Just a heads up.

Thanks for the responses.

Mark:
My caculations using the RC Head Calculator show 2100 GPH but I see you point. I should look to try and get 1000 GPH from my sump return pump and possibly 3000 GPH through the CL. The question then is how do I determine whether I get 3000 GPH through the CL when the calculator dosn't take into consideration the things you mentioned in your post.

When calculating the head loss on the CL I added 6 ft. as the pump will located just below the main floor to reduce sound. Should I not have done this?

Lost Mind:
My plans are to order a custom aquarium complete with holes in the rear panel of glass. No holes in the bottom. Thanks for the heads up though.

What do you think of using these pumps:

Closed Loop:
Sequence 4000SEQ19 / 4000 GPH at 0 head & 3000 GPH at 10 ft of head.
That should be plenty for 4 - 3/4" outlets.
The question is, is a 2" outlet enought to feed it?

Sump Return:
Velocity T4 / S4 1446 GPH at 0 head & 1000 GPH at 10 ft of head.
This should work well for a basement sump?

Just saying you don't need a huge flow through your sump if you plan the majority of the your displays flow from your CL. Your return pump can be smaller saving cost, power and reduced noise.

Not sure the proper way to figure CL flow from the RC calculator. Guessing probably something to do with area of outlets (4-3/4" outlets is about the same as 1-1.5") but if you have a CL you have zero vertical head. Suggest a post there (RC).

Might also find some help here, at the very least, lot of pictures.
http://www.oceansmotions.com/forum/

Some info on pumps for your sump return: http://www.wetwebmedia.com/ca/volume...rnal_Pumps.htm
and more links at bottom of article.

Not to steer you away from CL but have you thought about something like Tunze Streams?

Thanks Mark,

I have thought about Tunze Streams but would prefer to keep the display tank as equipment free as possible.

What kind of flow should I be considering for the sump - return to tank. Is 1000 GPH to much?

i'm not raining on your parade but i felt the exact same in planning my tank, i did not want equipment in the display tank so i went with a barracuda for a CL. the tank has been running for a month and i just ordered 2 tunzes 6100 and bought 2 wavy seas to mount them because the CL is so loud and annoying you cant enjoy the tank so i'm getting rid of the CL. it would have saved me time, money and a lot work to have just gone with tunze setup. but i'm not saying a CL is bad, maybe it will be good for you. just my thought

Sort of the same feeling here, for looks go CL. Had a 75g with three MJ1200, didn't want the same on my new tank. Just mentioned the Streams as you seem concerned about efficiency and flow. Since it sounds like you are placing the CL pump below the floor rather than in the stand you'll be cutting down on noise.

My CL pump is a Dart and it's below the tank. I still notice it when the house is quiet (can hear it humming now) even after the tank setup for months but if the TVs on or just talking it disappears. I considered having it in the floor/ceiling joists space directly below the tank but then it would have been where the HT is going, wouldn't of last there.

I have 75g sump and about 1000gph, seems totally fine. With my old pump could have 2000gph but restricted the pump back mostly because discharging that much back into the tank through a 1" pipe I was getting splashing and placing stuff was difficult. Going slower definitely found I had more crap settling in the sump.

Thanks guys

niloc16:
As Mark mentioned the CL pump will be below the main floor so I don't expect much noise. Fingers crossed.

Mark:
I think Im going to shoot for 1000 GPH from my sump return pump & 3000 GPH from CL. I may go a little larger and just hold them back a little with a valve.

As mentioned below I think ill go with ...
Closed Loop
Sequence 4000SEQ19 / 4000 GPH at 0 head & 3000 GPH at 10 ft of head
Sump Return Pump
Velocity T4 / S4 1446 GPH at 0 head & 1000 GPH at 10 ft of head.

What do you think of these pump brands?