Flow rate ?

I'm going to be building a 200g plywood tank w/2 built in overflows w/ Durso standpipes. Does anyone know if the size of the bulkheads and the standpipes detirmine the flowrate, or if it is the size of the holes or slots in the overflow? Plan on using 1" Bulkheads and 1 1/4 standpipes. Hoping for approx 600gph per. plan on using a 1500gph return pump.

 

600 gph is max for 1" bulkhead as long as the rest of your drain system can keep up. Would definitely recommend a double union ball valve on your return so you can adjust the flow. Adjusting the flow and might have to drill the standpipe top hole a little bigger to get the max flow with no gurgles, etc.

 

It's the size of the holes and slots of the overflow box... Just make sure your pumps are rated at less than the flow rate of the overflow. And yeah also what drewspuppet said about the 1" bulkhead.

 

I thought it was the overflow itself. Like i said I'm building them myself so really I have no idea what the flow rate will be, it's going to be trial and error I guess. If the flow was greater than the pump the sump will overflow. I would think I would need a bigger flow rate and regulate with a valve?

 

It is the overflow itself but a bulkhead can only take a certain amount... Just think of what would happen if your bulkhead was the size of airline tubing... it couldn't keep up.

Somewhere online there is a site that shows how to build an overflow box and calculate the flow rate based upon dimensions and other things. I came across it once, I'm sure if you google hard enough you can find it.

The sump won't overflow if the box is rated higher than the pump, the box will sync itself with the pump. You just don't want the pump to pump more then the box can handle, that is where you will have a problem. This is all crazy and hard to think about, I know, I've been there done that and lost sleep trying to figure out how it all works.

 

Well then with that being said, then I suppose i can drill holes or slits in the overflow any size I want then? Thae standpipe shouldn't flow more than 600gph and if i put a valve on the return pump I should be able to regulate flow if i have to. Agree?

 

Agreed but like bc219 said your sump wont overflow, your DT will if your return pump is rated for lets say 1000GPH and your overflow and standpipe can only handle 500GPH then you will need some type of valve on your return. But with restricting the pump back to the DT that will put stress on your pump and make it run warm raising your tank temp. Are you putting in 1 or 2 over flows??? On a 200 g system i would use 2 over flows, one at each end then you will have lots more flow that you can deal with.

 

Yes, as originally stated in the first thread I am building 2 and was planning on using a 1500gph pump for return from the filter. Was also planning on a seperate closed loop system for circulation. Do you guys think that is too large of a pump? It will have to pump a good 4.5-5' rise.

 

Sometimes you can go the manufacters website for your pump and they may have a chart that shows how many GPH it will lose as the hight gets higher. I think it should be fine though. You could always put a valve on both returns just to be safe.

 

If there is any concern about restrictions caused by the bulkheads and standpipes make them bigger. I dont know the max flow rate on 1.25 or 1.5 bulkheads but it is faster than 600 gph. If you have a 1500gph pump and two 600 gph bulkheads, assuming no other flow restrictions, then you will have to use the valve to cut down the flow by 300gph. If you get 800 GPH out of the 1.25 bulkheads (SWAG not a real number) then you will get a max of 1600GPH draining. Your only pumping 1500 GPH up so that is the real life speed of the draining.


My rule of plumbing is always make the drain as big as you can because stuff builds up in there and will slow the flow even more. There is no reason not to overengineer it from the start besides it gives you wiggle room for upgrading later =)