Overflow and Drain Size in 240G?

[Inkedsphynx]

I'm pretty much new to reefkeeping, so I'm not quite sure how I should go about setting up the overflow system in the 240 I'm going to purchase. It's hard to piece together the information since I know there are quite a few factors involved. It seems that the size of my overflows and drain pipes should relate not only to tank size, but how much flow should be going through the tank, and I'm unsure of that as well.

The dimensions of the tank I want to order are 72x24x31 (LxWxH). I want to play dual overflows in the back corners, and I'd like to minimize how much space they take up. So, basically I'm not entire sure how to go about this entire portion of the setup. Also, what size drains should I have in there? I am figuring about 2 inch in each overflow. Plus, what size should my return plumbing be, which should also run back up through the overflow, correct?

Thanks in advance for any help!

 

[Inkedsphynx]

If anyone could at least point me in the direction of some literature (online or not) that addresses these subjects, I'd really appreciate it.

Thanks!

 

[bertoni]

http://www.reefcentral.com/calc/drain.php

That calculator should help.

I'd probably target at most 1000 gph through the sump. The calculator gives this estimate:

Using the following input parameters
Gallons per Hour = 1000

Drain and Overflow sizes are calculated as
Recommended minimum drain pipe diameter = 1.31 inches
Recommended minimum linear overflow size = 15 inches

You'll need to choose a flow rate.

 

[bertoni]

Ooops, meant to add that replying to your thread takes it off the unanswered list, which can delay a response. Usually, they all get scanned, anyway, though.

 

[McBeck]

Also, the returns may be dictated by your return pump's outlet size. You might want to talk to the tank manufacturer about return size suggestions. Hopefully s/he has made a few tanks and can help you make an informed decision.

 

[Inkedsphynx]

Thanks for the info! I noticed that calculator and plugged a few numbers in, but I wasn't sure what type of flow I should shoot for. Is 1000 gph through a tank that size sufficient for corals, or should I perhaps compensate with a closed loop system to create more current in the tank, in which case a 1000gph turnover should be sufficient to properly filter the tank?

 

[bertoni]

You'll want a closed loop or powerheads, etc. I personally wouldn't try to provide all the tank's flow through the sump, since that's expensive and bubble-prone, IMO.

 

[NeilPearson]

I agree I would do about 1000 gph through the sump and the rest through a closed loop.

On a side note.... I would reconsider the tank size (72x24x31 (LxWxH))

My big tank is 84x24x24 and I couldn't imagine it being taller. Even at 24", I can barely touch the sand. Deeper would be a pain. Also with only 24" width, it is difficult to aquascape. All the rock structures have to go pretty much straight up. It is hard to stack rock up to fill the tank with only 24" height. If I had to fill 31" I would definitely need a wider base for the rock.

 

[sushiking]

I would oversize the bulkeheads/drain pipe size: Two 2" bulkheads plumbed into 2 overflows.

You can calculate the size of the overflow by realizing that you need an equivalent area to the bulkhead hole area or pi*radius^2
which for a 2" hole is pi*1^2 = pi = 3.14 square inches. If you use 1/4 inch wide slots in the overflows that are 1 -1/4 inches high with the water level at 1/2 inches from the bottom of the slots then you need :

Area of 1 slot = 1/2 * 1/4 = 1/8 sq in per slot
Total number of slots = 3.14/ (1/8) = 3.14 * 8 = 25 slots
Length of overflow = 25 * 1/4 = 6 inches minumum or you could use 4 inch wide overflows and put some slots on either side to make up the required area.

Since there are 2 overflows, if one clogs the other will handle the full load....100% safety factor built in!

 

[yoboyjdizz]

<a href=showthread.php?s=&postid=7332881#post7332881 target=_blank>Originally posted</a> by NeilPearson
I agree I would do about 1000 gph through the sump and the rest through a closed loop.

On a side note.... I would reconsider the tank size (72x24x31 (LxWxH))

My big tank is 84x24x24 and I couldn't imagine it being taller. Even at 24", I can barely touch the sand. Deeper would be a pain. Also with only 24" width, it is difficult to aquascape. All the rock structures have to go pretty much straight up. It is hard to stack rock up to fill the tank with only 24" height. If I had to fill 31" I would definitely need a wider base for the rock.

I love the 30'' inch height makes it look better..yeah u might need a step ladder from time to time but getting a little wet is not going to hurt you. But if i had to chose i would take 30 inches in width over height anyday. But my tank is 72x30x30 so i got best of both worlds.

 

[yoboyjdizz]

as for a return you only want a good 3-5x time turnover through your sump so anywhere between 950gph-1200gph will be what you want to shoot for.