What size bulkhead "Out"?

[Jason]

Im in the process of building a 55 gal barrel up-flow filter and am going to run 1-1/2" PVC to it with a 1,200gph pump and am wondering how large of a bulkhead should I run for the gravity fed outflow? I was thinking 2" but Im not sure what the equation is to the whole pressure gph vs gravity out flow thing lol. Thanks

 

[sissy]

Your pump may not be big enough for that sized barrel .Not sure how far water has to travel from the pond to the barrel but that will also cut down on gph also .I have a 2900 gph pump for example and a 60 gallon filter down flow and pump goes to filter and small amount goes to uv and small amount to waterfall pond and it is barely enough .It only has to travel 4 ft to the filter .I have 2 - 1 1/2 inch outlets on filter .Hoses to uv and water fall area are only 1/2 inch hoses and to the filter 1 1/2 inch hose

 

[slakker]

I found this video useful when I first setup my marine reef tank, and helped me with the pond too. Good example of what to expect for pressure pump in vs. gravity fed out...

 

[Meyer Jordan]

Im in the process of building a 55 gal barrel up-flow filter and am going to run 1-1/2" PVC to it with a 1,200gph pump and am wondering how large of a bulkhead should I run for the gravity fed outflow? I was thinking 2" but Im not sure what the equation is to the whole pressure gph vs gravity out flow thing lol. Thanks

If the outlet was the same size (1 1/2") as the inflow, the water velocity should be identical. As you increase the size of the outflow, the velocity will be reduced.
As Sissy mentioned, your pump may be too small, especially if it is a mag-drive. Check the manufacturer's Performance Curve Chart for the pump that you are planning on using.

 

[Jason]

Sissy, the 55 gallon barrel will be right behind the patio pond about 6-7' feet away from the pump and then it will out flow from the top of the 55 into the waterfall box and into the pond which will be about 2' max from entering the pond. I was wondering the same thing about how much flow I would lose, although I do have the 2,100gph pump in case the 1,200 falls short

Thanks Slakker, that gave me some insight to how it works better. I went through that last year with a 1" bulkhead feeding a 30gal container pass-through style filter and I had to drill at least 2 more 1" bulkheads at the end because it kept over flowing with one, even with 2 of them the water still stayed about 1" above the bulkheads as I guess it needed a little extra pressure to stay that level.

 

[Meyer Jordan]

I was thinking pressurized filters.Obviously your is not. My bad!

 

[slakker]

Ya, I would go about 2x the input line and since it's a simple return, going larger wouldn't hurt (unlike in an aquarium)...

 

[DrCase]

A 2" bulkhead & pipe won't have any trouble gravity returning 1200 gph

 

[TAHOE]

I have a 30 gal barrel filter, water comes in the top through a 1" pipe which is elbowed and piped to the bottom so the water swirls in a vortex style then water flows up through lava rock and out a 2" outlet. I tried an equal outlet I think and I overflowed barrel, had to jump top a 2". General rule I think is usually a 1 1/2 times bigger outlet over inlet, I doubled it to insure no overflow. My submersible pump in pond is only a 250 or 350 gph and has to lift almost 3' and does fine.
I have a thread in the DIY section somewhere from last summer or fall. "30 gal drum filter" or something like that, can't remember how I titled.