Overflow box capacity

[murph]

My overflow boxes have a one inch drain. How many GPH can a box like this handle. I thought it was 600 but I have a 660 GPH pump on it now with no problems. Grant it it has about a 45 inch head to deal with.
I am in the market for some pumps this weekend and would like to get as much flow as possible without ending up with water on the floor. TIA

 

[marvida]

It probably is close to 600 gph. As you mentioned, there are factors which diminish the flow from a pump. Their rating is probably measured righ out of the pump without any piping attached. There also maybe a little fudge factor built into the rating of the overflow box.

 

[hurt]

Is your return pump below your DT. If so, it's probably at least 3-4 feet height on the return pipe to your DT. If your return pipe is 3 feet up with 3-4 90's, I seriously doubt your return pump is even doing 400 gph.

 

[hurt]

Never mind, I'm blind-you said a 45 in head. And how many 45's or 90's? Either way it is probably only doing around 400 gph.

 

[murph]

There are 4 90 degree or right angles in the plumbing and when I rework things this weekend the head will be reduced to about 36 inches. So by what you are saying I could easily get a 1000GPH pump to provide max flow??? Thanks for the reply.

 

[hurt]

Yeah, around there. The pump I run on my return is rated at 1050 at 0 feet. It goes through two 45's, two 90's, a SCWD and probably 4 feet back up to my DT. My overflow is rated for 1200gph. It has two 1 in drains. However I only use one of the two U-tubes in the overflow itself. So, it's probably doing close to 600gph. Also if you can use 45's instead of 90's where possible, do it. Here's a picture of how I used the 45's.

 

[murph]

Thanks guys great replies. I have gone over this with 3 or 4 different LFS employees and they don't even act like they understand what I am talking about. Makes me wonder where they find some of these people. I was beginning to think it was me

 

[escape2thewater]

from what I have found through hours of experimenting is that the main flow resrtictor, at least on my overflows is the j tube. I have been experimenting with trying to run dual j tubes to improve flow but have not been able to get it to work consistantly. The overflow drain keeps up with it just fine and boy does it flow some water! The prob ive been haveing is when you cut power to the pump the dual tubes loose siphon too easily to be reliable. Anyway my point is if you can find a way to improve your j tube size or quantity your overflow will ikely flow much more then it does now. Im still working on mine, if I ever figure it out ill let you know!
Escape
:happyfish

 

[benter]

I have a 1200 gph overflow with 3 j tubes in it , and I have never had a problem with them loosing prime..I have no Idea why if that happens on a regular basis it hasn't happeneed to me..I even have 2 tubes in my 600 gph overflow with no syphon problems..Wonder why??

 

[hurt]

when you cut power to the pump the dual tubes loose siphon too easily to be reliable.
You are doing something wrong then. Mine will never lose their suction. I bet your drains in the outside section of your overflow are not high enough, add another inch onto the height of them and I will guarantee they won't lose suction.

 

[acrylic51]

To give you and idea of what the box will handle take measurements of the box LXW and bulkhead size.......Meaning lets say the box is:
8"l l
l l 8"
l______10"_____l
Take your measurements and go to the other famous site and use their calculator and plug your numbers in along with your bulkhead hole size and it will give you a pretty good idea of what the overflow box would handle.......It's more to it than how many "J" tubes and such you have it has to do with linear skimming area of the box

 

[promisetbg]

We built our own J-tube out of PVC...works much better,handles alot more water,and never loses syphon.

 

[acrylic51]

Cool work, but again the answer really doesn't boil down to the size of the "J" tube....You have to have the skimming area to draw the water into to make any style "J" tube work regardless of size of the tube and the bulkhead has to be sized accordingly as well...

 

[murph]

Well I thought I would know for sure by now but everything in my neck of the woods is on hold until we find out how big a b&tch Wilma is going to be. I am over a hundred miles from projected land fall so I am hoping for the best.
I need to move the tank anyway and its pretty lightly stocked with no corals and relatively inexpensive fish so if I lose everything due to power loss it wont be that big of a disaster but I will have a bigger project on my hands than simply finding the right size pump for my OF and plumbing. Wish me luck I may need it.
To make matters worse one of my tank raised maroons came up MIA this Saturday. One of my first fish that I put in the tank and one that I truly believed was "bullet proof". I guess when it rains it pours.
I am starting to get that feeling of impending doom. I hope I am wrong.

 

[promisetbg]

Hey...chin up!Think positive!!

 

[squidd]

To a point, I agree with Acrylic about the "linear inchs" , obviously, you are not going to get 1800gph flow thru a 6"X6" cornerbox (12 linear inchs) without some turbulance and bubble issues...
But to "Fine Tune" the overflow you already have, to the maximum potential it has (often higher than mfg. rating) you can "size the U tubes to your advantage...
Check outthis link on "sizing" U tubes...HTH..
https://www.saltwaterfish.com/vb/show...=sizing+u+tube

 

[fireykat04]

Murph,
I remember you saying you run the Fluval 404 canister filters. I am wondering if you ever had a problem with them not sealing. When I shut my mind off to change the media, unless I push the lever up that stops the water flow it now leaks out. I don't remember it doing that when it was new. I am afraid if I have an electric outage I'm going to come home to find my whole tank drained in the living room floor! Any thoughts? It's only about 6 months old. Should I get a new O-ring? Thank you in advance for your help. :notsure:

 

[murph]

Sorry fire that wasnt me with the fluval.
I purchased a 990 GPH pump and its to much for the box now. Will adding a second U tube help or is it more to do with the size of the box itself. Box is 8 inches wide and adding a second U tube would total 2 inches. Drain I am stuck at, at 1 inch. For now I am useing a ball vavle to restrict flow a tad so the tank does not overflow.
Hurricane left me alone

 

[acrylic51]

Try the 2nd "U" tube.....The worst thing that could happen is that the one of the "U" tubes won't continue to hold a syphon.....You'll probably have to open the valve up a bit and play with it and watch it for a while....