# Matching Overflow/Pump rate



## 65galhex (Nov 5, 2008)

I am setting up my own wet/dry filter system but I want to use my powerhead 110 as the pump for my return. It pumps at 935gph and my question is what kind of overflow do I need for that? How do I figure out what the flow rate of the overflow box is? I would also prefer not to drill my 150 gal as I already have fish in it. Sorry if I am asking dumb questions.


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## THE BLACK PIRANHA (Dec 8, 2003)

You say your pump does 935 gph and thats more than likely at 0 ft of head, and you will probally have 4 or 5 ft of head. So find out what your pump will do at 5 ft of head and get a overflow that matches, look on ebay they have just about any box you will need.


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## 65galhex (Nov 5, 2008)

What do you mean by 5 ft of head? Sorry for the noob wet/dry questions.


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## Plowboy (Apr 9, 2008)

head height is just how far the water has to be pushed up before it goes over the top of your tank. Basically the bottom of the sump/filter to the top of the tank


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## THE BLACK PIRANHA (Dec 8, 2003)

The head pressure is how much return hose it has to push the water up to get it back to the tank. With any pump the farther it has to push water the lower the gph will be.



Plowboy said:


> head height is just how far the water has to be pushed up before it goes over the top of your tank. Basically the bottom of the sump/filter to the top of the tank


I got a call and was a little late hitting the reply button.


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## 65galhex (Nov 5, 2008)

ahh ok that makes sense.... I would say it is about 5 feet. is there a formula that i can use to figure that out?


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## Plowboy (Apr 9, 2008)

Reef central has a calculator, but they might not have power heads on the list.


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## THE BLACK PIRANHA (Dec 8, 2003)

What brand and model # is your pump?


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## Plowboy (Apr 9, 2008)

Just checked and they dont have it. Heres the link anyways.

You can check the flow at that height by setting a full 5g bucket and running the water into the tank with the pump. Time it, then take the time it takes for the bucket to get empty, divide it by 3600. Then multiply that by 5g.


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## Ægir (Jan 21, 2006)

And as for "matching" your overflow rate to your pump... you dont. You always want your overflow box to be capable of handling more GPH than your pump after head loss. An overflow is basically like the drain in your shower, and your pump like the shower head. NO matter how low or high you turn it on, the drain will always remove the extra water and be capable of slightly more as protection from a clog or debris.

Most likely your powerhead wont be capable of providing the turnover you need, nor do they work very well... Ideally you would have 1200-1500 gph after head loss, and an overflow rated slightly higher.

Watch Ebay for used overflow boxes, you can get them for fairly cheap. But drilling your tank would be the ideal route...


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## NegativeSpin (Aug 1, 2007)

http://www.aquariumguys.com/cs150overflow.html


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## 65galhex (Nov 5, 2008)

THE BLACK PIRANHA said:


> http://www.aquariumguys.com/cs150overflow.html


Thanks man, what pump do you recommend with this?


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## Ægir (Jan 21, 2006)

Heres a good deal on a used one... Clicky

and heres some more Clicky

Just look for a pump online that you can find a flow chart for... most will have them. Then look for one thats 1200 or so GPH @ 5' head


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## NegativeSpin (Aug 1, 2007)

Skunkbudfour20 said:


> Heres a good deal on a used one... Clicky
> 
> and heres some more Clicky
> 
> Just look for a pump online that you can find a flow chart for... most will have them. Then look for one thats 1200 or so GPH @ 5' head


The second overflow looks good and for 25 bucks!


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## philbert (Mar 8, 2007)

i have too been thinking of a doing a sump. so you are saying if you have a 1000 gph over flow that you want 1200 gph turn over at whatever the head height is? how does the sump stay full then if more is pumping out than comingin?


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## Plowboy (Apr 9, 2008)

philbert said:


> i have too been thinking of a doing a sump. so you are saying if you have a *1000 gph* over flow that you want *1200 gph* turn over at whatever the head height is? how does the sump stay full then if more is pumping out than comingin?


The overflow has to be able to handle more than the pump. Switch those two numbers around.


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## NegativeSpin (Aug 1, 2007)

I worked out a good approximation with the Bernoulli equation for different diameter bulkheads at different heights.


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## philbert (Mar 8, 2007)

Plowboy said:


> i have too been thinking of a doing a sump. so you are saying if you have a *1000 gph* over flow that you want *1200 gph* turn over at whatever the head height is? how does the sump stay full then if more is pumping out than comingin?


The overflow has to be able to handle more than the pump. Switch those two numbers around.
[/quote]

yea sorry thats what i mean. so how does a 1200 gph over flow matched with 1000 gph pump not over flow the sump if water is coming in faster than it is leaving?


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## NegativeSpin (Aug 1, 2007)

The overflow will only drain your tank to a certain point and if the volume contained in your tank between the maximum height and when flow stops is not greater than the volume of the sump above operating level than you are good to go.... Fail proof. Actually if you don't protect against a clogging overflow you need to only use the volume of the tank filled to the top for the water for both the tank and sump.


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## Plowboy (Apr 9, 2008)

The overflow doesn't constantly run water over at 1200gph. It will vary to match the pump. It has a front chamber, in the tank, that determines the water level in the tank. The water has to be high enough to "overflow" into that box to get to the siphon that will then take it over the back of the tank. Ok, so the water level is going to be right at the height set by the top of the overflow box. When the level tries to get higher it will just overflow into the first compartment were the siphon will take care of it. Really all the pump is doing is pumping water into the tank causing the water level to go up. The faster the pump runs, the faster the water level is trying to raise, so the faster the water will go over the overflow where the siphon, as always, will take it over the back of the tank. After all of that there is a tube in the back box that will take it down to the sump.

The siphon tube stays primed and ready because it is air locked on both sides by the boxes on both sides. If you look at an overflow box and pay attention to were the water levels will be you will catch on. I think skunk has a good pic to help explain this part?!?!?! If he does, I'm sure he'll see this in a bit and post it. Ill go see if I can't find it until then.


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## Plowboy (Apr 9, 2008)

There you go. The smaller box would be the front one (or in tank). The top of that is what determines the water level. And the red tube would lead to the sump. The red line is the water level.


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## NegativeSpin (Aug 1, 2007)

^^The flow rates I gave are for when the level raises high enough for the water spilling into the bulkhead to form a continuum in the return hose.


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## philbert (Mar 8, 2007)

thanks for the explination. that was great i really get it now and it makes so much sense haha. i just never really needed to know about sumps bc i never had one.


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## Ægir (Jan 21, 2006)

philbert said:


> i have too been thinking of a doing a sump. so you are saying if you have a *1000 gph* over flow that you want *1200 gph* turn over at whatever the head height is? how does the sump stay full then if more is pumping out than comingin?


The overflow has to be able to handle more than the pump. Switch those two numbers around.
[/quote]

yea sorry thats what i mean. so how does a 1200 gph over flow matched with 1000 gph pump not over flow the sump if water is coming in faster than it is leaving?
[/quote]

As stated Water isnt coming in any faster than the pump is putting it in the display... the overflow CAN handle 1200gph, but always flows at the same rate water is being pumped in... like i said think of it like your shower, the drain will just flow when water is coming in at any rate, and when its off, the floor of your shower would be the displays top level, water cant flow out unless it raises above that level.

Love the pic BTW who made that?







... that is more to explain how to properly setup an overflow box so it will keep its prime in a power outage, heres the video that goes a little more in depth.



The downfall of the U tube overflows, is that people dont put the small standpipe on the outside so the water level drops below the U tube, and breaks the siphon.... when water starts it just overflows the display instead of following the drain. If setup properly, its completely silent, holds a siphon (both ends of the U tube are under water ALWAYS), and is almost failsafe (mine ran for years, then the U tube cracked because of UV damage from halides i think)

Good luck man!


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## Plowboy (Apr 9, 2008)

philbert said:


> thanks for the explination. that was great i really get it now and it makes so much sense haha. i just never really needed to know about sumps bc i never had one.


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## 65galhex (Nov 5, 2008)

Wow guys that is awesome. That reallllly explained a lot to me. I really appreciate it! So now that I have the flow rate solved and the overflow solved what brand pump do you guys recommend? 
I just happened to see something like these.....

http://www.drsfostersmith.com/product/prod...mp;pcatid=20170
http://www.drsfostersmith.com/product/prod...cfm?pcatid=4590


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## Ægir (Jan 21, 2006)

The second one, the mag drive are great pumps!

I would use the MD 12, with a properly setup overflow box you will be able to handle the 1100 or so GPH (thats at 4 feet)

When you are ready to do the plumbing, just after the pump add a T and a ball valve so you can divert water to the beginning of the sump if you have too much flow for your overflow box or your likings. You should also use some sort of backflow prevention because when the power goes off, your return line becomes a siphon and will fill the sump. You can use a small hole on your return line just below the water or something similar


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## CLUSTER ONE (Aug 2, 2006)

65galhex said:


> I am setting up my own wet/dry filter system but I want to use my powerhead 110 as the pump for my return. It pumps at 935gph and my question is what kind of overflow do I need for that?*just look around at reviews on different overflow boxes.* How do I figure out what the flow rate of the overflow box is? I would also prefer not to drill my 150 gal as I already have fish in it. Sorry if I am asking dumb questions.


Most overflows will say how much they can do, but a 1000gph overflow should be plenty. 935gph is for at a horizontal level. the more it has to pump up the less the gph is. Heres a stat on what i mean from my brand sump pump:
0' 975gph 
1' 780
3' 740
5' 685
7' 610

As you can see as soon as it has to pump water vertically it loses alot of gph. Im assuming it will have to be pumped back up about 3-4'? larger overflow then the pump can do is fine to as i have a 600gph overflow with a pump thats 350pgh at ground level. Just larger ovderflows take up more space. There are general calucualtors out there if you search to give to an estimate of how much gph you will lose at different heights.

Get a mag drive supreme. There sweet. Ive heard good things about eheim, but their pricy and i dont think they are even in large sizes


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## 65galhex (Nov 5, 2008)

Thanks sean! I am going to pick up one of the mag pumps and then get one of the eshopps overflows.

What is the ratio for the size of the actual sump? like 20 gal container for a 150 gal tank or what should I look for?


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## CLUSTER ONE (Aug 2, 2006)

65galhex said:


> Thanks sean! I am going to pick up one of the mag pumps and then get one of the eshopps overflows.
> 
> What is the ratio for the size of the actual sump? like 20 gal container for a 150 gal tank or what should I look for?


Honestly im not totally sure, but i would more go by the largest tank you could fit under the 150 and still have plenty of room for maitnence. So a 55 would be good as anything bigger would be as wide as the 55. There are also 45 and 33 with the same footprint as a 55 just lower. Just think bigger tank, more water volume meaning stable tank and larger media capacity.


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## 65galhex (Nov 5, 2008)

So if I had a 55 gal container on the bottom with say a 5 or so gal compartment/bucket for the filter media, the mag 12, and the eshopps 1800....... that would be a pretty ideal setup?


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## Plowboy (Apr 9, 2008)

Yeah go as big as you can. 55g would be around the size I would put under mine, but I think you could possibly sneak by with a 29 or 33g if you had to. Many people say 1g of bio balls will handle 30g of tank so your going to need 5g minimum of bio balls/other media, but I would go with more than that. They arent expensive at all. Heres some, $40/5g and $80/20g. bigals also has them packaged 5g at a time for $30.


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## Ægir (Jan 21, 2006)

65galhex said:


> So if I had a 55 gal container on the bottom with say a 5 or so gal compartment/bucket for the filter media, the mag 12, and the eshopps 1800....... *that would be a pretty ideal setup*?


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## CLUSTER ONE (Aug 2, 2006)

`google "melves reef" and that wil ltell you tons on sumps and overflows. Dont worry, you arnt alone, it took me a bit to grasp how overflow boxes work


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## 65galhex (Nov 5, 2008)

nice! ok thanks I was starting to feel like I was straight dumb..... or I was missing something haha


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