One or two Corner Overflows?

[Fishobob]

Gday,
Well im now looking at having my tank built and it will be 4 by 2 by 2 foot so roughyl 432 litres or 90 gallons in US terms i think. Anyway I'm looking at having a sump and maybe a refrigerum with corner overflow/s.
I was wondering if I should run with a single corner overflow or have 2 overflows, 1 in each back corner. I was wondering what are the advantages of having 1 or 2 and also the disadvantages of the two.
I'm also wondering about what size holes I should have drilled. I have heard that 2 inch holes and bulkheads have certain advantages over smaller holes. If you could tell me what you think, whether larger or smaller, and the reasons why I would appreciate it.
Another thingy I was wondering about is where you guys have your return pipe from the sump back into the tank. I have seen some coming out at the top of the tank on one side and also some coming in at the bottom of the tank and the pipe going right up to the surface of the water. Which do you guys think is best or where do you guys think is the best place for the return pipe to be?
If you could reply and give me some insight into how I should set my tank up I would be grateful!
Cheers,
Fishobob

[Ninong]

Fishobob,

If your tank measures 4' x 2' x 2' it would be 120 US gallons, 100 Imperial gallons, 451 liters.

Most tank manufacturers over here build that tank with two corner overflows. The usual configuration includes a 1" drain bulkhead and a 3/4" return bulkhead in each corner overflow. That is adequate for most people but it is possible to go with even more flow capacity by making each of the drains 1.5" and each of the returns 1". My own tank is 120 gallons but it has a single corner overflow on the left side with a 1.5" drain and a 1" return. I also have returns running through SeaSwirls. http://www.sea-swirl.com/ Over here, most reeftanks are built with corner overflows (or center overflows) that have the drain and the return holes drilled in the bottom of the tank. Something like this: http://www.oceanicsystems.com/products_aq_rrtanks.html

The advantage of having two separate overflows is that you always have a second one working if anything should happen to block up one of them. The disadvantage is that two overflows take up more tank space.

[Papa Doug]

I like the two overflows, one in each corner. Better surface skimming. I tried a large center overflow, with two stacks. Never liked it as much.

I have a friend who has a 120. He has only one corner overflow, but it contains two stacks. This gives him more tank room, yet the reliability of the two overflows, mentioned by Ninong.

Another friends 120, has just one. He runs a Mag9 as a return. I have found a 2in. drilled hole, takes the standard 1 1/2 in. bulkhead. This will take 1 1/4 in. plumbing. So if straight stacks are used, you would have 1 1/4 in. stacks and if you went with Duraso, it would give you 1in. stacks.

I have run up to 500gph on a 1in. stack with no problems.

[Fishobob]

Gday,
Thanks for the replies. I am thinking of going with 2 2inch corner overflows and I'm still not quite sure where to have my return. What do most of you guys run with? Also if you could give me a back description of the plumbing on your tanks I would appreciate it.
Thanks

Fishobob

[Papa Doug]

Some drill the tank for returns, through the bottom and up the overflow chamber. I have done that before. This one just runs over the top and down to the waters surface.

[NewMariner]

My newly acquired 180g Tank came with one corner overflow with a 2 inch drain and I believe to be two 1 1/4 returns. The larger tanks I have always seen have always had two overflows...You lose alot of tank space with that setup. I like having just one overflow....and with a 2 inch drain you really dont have to worry about the drain getting clogged...

[Bughead]

I have a 180 with a single overflow. It's just like NM discribes, with a 2" overflow and 1 1/4 return. It was totally DIY, that's why it has only one overflow. The thing is glass and weighs at least 500 lbs empty. Having the glass place drill 2 wouldn't have cost that much more, but positioning and repositioning it on the stand to drill a second one would have been hell. The return goes over the top, not drilled.
The thing that is most troublesome is the return, which sometimes gets sluggish. If this were a reef tank,I'd add another return. I may do that in the future, but the circulation is good anyway.

[NewMariner]

Hey Bughead,

What are you using as your standpipe on that 2 inch drain? Im talkin with Rich Durso(Durso Standpipe) and he says a 2 inch Standpipe might not work to get it quiet....What are you using?

[Bughead]

yes, this was quite the project. Since this was totally a DIY on a budget, I had to get real creative. I made a stack out of 4" PVC connecter pipes. I cemented them together with aquarium epoxy and sealed the seams with sealant. I covered the outside with green plastic webbing used in making little rugs or cross stitch crafts. So the main problem when we started up the thing was the noise. GLUG GLUG GLUG! We tried several ways of baffling, pieces of plastic netting, filter fiber, etc. It helped a little, but still glug glug glug. Then I was messing around my home away from home, Home Depot. I saw this green drain thingy, it fits perfectly into the end of the 4" pipe, and breaks up the water flow like a picket fence. It stopped the noise immediately. So now there's no noise at all from the overflow. After feeding the tank I hear a louder glugging noise in the sump for a few minutes. I don't know why, but it's of short duration and not bothersome.

[Fishobob]

Gday Fellas,
Well I've decided on the two corner overflows. My lfs guy tried to advise me against it but all you guys tell me that two is better. So I'll go with you guys, my lfs guy doesnt know much anyway.
Cheers Fishobob

[Reefland]

Good choice; you won't be sorry. The additional flow capacity will make all the difference in my opinion. My 48x18 (75 US gal) has one overflow and I can't get it to take more than ~1200 gph.

Scott Z.

[smackwater]

hey scott,

thats 16x turnover. what turnover rate are you looking for? I thought that 10x-12x was the standard. what turn over rate do you think that 360gal I bought should have. I might have to refigure my pump config. Was planning on using amp master 3000 for built in cloosed loop and may be a/m 2700 for return. would apreciate advice from anyone.
scott do you have alot of bubbles in the tank from the high turnover?
that seems like alot of water going though a 20? gal sump.

-smackwater

[Reefland]

I am looking for as much current as I can get. I don't know that we can "over power" our tanks when going with SPS and I have talked with people who try for 20x turnover. 10x turnover is one of those rules like watts per gallon that isn't really a rule, just a way to get an idea.

npaden has a 415g tank and used 2 AMP Masters and was not pleased with the flow, granted his tank is a bit bigger than the one you are planning. You might look for something a bit bigger to provide more flow. I would reconsider the AMP Masters, I have read several threads regarding the seals going out in the pretty early in their life. Here is the link to his plumbing page, it might give you some ideas, I don't know.
http://www.padens.homestead.com/tankplumbing.html

I do have some bubbles going through the tank with that turnover but I don't think it's sump size as much as it is the plumbing itself. The sump has a couple of baffles in it which eliminates the bubbles from the drain but somewhere in the plumbing they are generated again. I was plumb through the return behind the overflow but recently changed to 2 1/2" flexible lines running over the back of the tank. This helped with the bubbles but did not eliminate them. This is something I am still battling.

Scott Z.

P.S. Did you get my e-mail response?

[smackwater]

reefland,

If your talking about the reply about the frags, glad to help


was over at that new store on blakenbaker access. He is using ampmaster 3600 for return on 1 of the tanks, scott I couldnt tell it was running tell I touch it and then it was still difficult. That is why I was leaning toward the ampmaster. plus the sales pitch had'nt heard about all the bad rep.

How about sequence pumps, what have you heard of them? I've noticed they seem prices, but in this hobby its cheaper to get it right the first time.
is'nt it passed your bed time?

-smackwater

[Reefland]

Passed my bed time? I'm still at work! Yup, that was the e-mail I was talking about.

Your right, I believe they are quite but again the concern is the seals going bad. I know golfish experienced this and others as well. If you go this route, you might want to contact Dolphin and see what they are doing about this.

I can't help you out with the Sequence pumps, I haven't heard anything about them.

Scott Z.

[golfish]

If its not too late here's what I would do...

Make it a single center overflow about 3-6" off the back glass. This way you can utilize all 4 sides of the overflow and hide your intakes, outputs, pumps, closed loop blukhead, internal closed loop pumps, what ever behind the overflow. I saw a tank like this a few months ago and thought it was a great idea.

I feel the Amp Masters are still the best bang for your buck. I just wish their customer service was a little better.

[Ltspd]

If the overflow is feeding your sump then the most you can pass thru the average sump is about 1200gph without creating bubbles. Why would you need more than that? I had 2 overflows and I am removing both going to 1 in the center of the rear of the tank. IMO its extra space removed from the tank.

IMO all you need is 1 overflow as Mark suggested above.

The seals in the Dolphin pumps are crap. I replaced 2 very rusty ones in my late AM3000's. Hopefully the ones I replaced them with wont rust and will work a bit better for the current owners.

[GLD]

To avoid losing valuable tank space to overflow(s), I have been considering cutting slots in the back of my tank at the water level and then attaching overflow containers to the back of the tank. This would allow water to overflow out of the tank in the same manner that it flows into the standard overflows, but all flow would be leaving the back of the tank.

I have not tried this yet, but was told by somebody that Professor Joshi at some university in Pennsylvania actually has done this.

As an aside, what are the dimensions of the 180 gallon tanks mentioned in the earlier reply's to this topic. Is anybody using a tank that is 30" or 32" rather than 24" from front to back?

[Bughead]

My 180 is 72" x 32" tall x 18" front to back.
On our 55 gal, the overflow is on the side at the water line. This is because the tank is to be built-in and there is no access to the back. Also we're not taking up space by having the corner overflow with the hole in the bottom. The only problem was that it was real noisy. The bulkhead is only 3/4 ", and the gurgling was so bad that I'd have to turn the pump down via the ball valve in the evening in order to hear the TV in the other room! I tried lots of different positions, screens, etc. but nothing helped. Finally I thought that maybe a larger area the water goes thru would help, so I put a 1" elbow for the water to flow into. It quieted it down by 90%.

[casey]

you guys are all wanting to much flow I have one corner on my 90 and it is perfect flow