Backyard Aquaponics
A place to discuss aquaponics

I understand from building outflow plumbing in my house that there is a point where larger pipe diameter actually slows sediment and smaller pipe size may keep solids moving. My lift will be around five feet to the water level of my FT. Gravity flow. anti-siphon setup. Sump pump size 1200 gph. question is; this for this much gravity feed lift would 4" pipe be okay to start? I can reduce it easier than make it bigger later as the FT walls are concrete and rock.

Boss, at 20 gpm, I'd think a 2" would be better.

Thanks Coach, I'll do it with the smaller pipe. I kinda had a feeling.

2" will drain 20 gpm, a 3" 45 gpm

I always run 90 mm with no problem

No 90 mil here , either 3 or 4" 77 or 102mm appx. I'm just going by Timmons drain and pump guidelines. You could use a large SLO, but you do risk have solids collect if the flow is to slow, like you mentioned. If you thought about increasing the pump/flow, you could use a 3" and then keep the horizontal piece as short as possible and maybe a clean-out Tee judt in case?

Hiya boss, I use 90mm stormwater pipe in the 3kl tank but the volume of water travelling thru the pipe is governed by the size and quantity of holes at the base of the slo and of course the volume supplied by the pump.
IMHO going larger is better because it's easier to increase velocity with a larger slo than decrease with a smaller slo
I think that makes sense?
Not sure how you can add a slo to your build and keep it aesthetically pleasing though.

The 50mm SLO in my 4500l tank works perfectly well. I'll probably use 2 X 50mm SLOs in the 9500l tank in my new system.

thanks everyone

I tried to gravity feed initally with a 40mm pipe in my FT, it wasn't big enough and would overflow before it dropped enough water. 90mm works like a charm now.

I'd trust Coach's calcs though

I kind of thought so. I see from that presentation PDF that two outflows are common. Perhaps as Monte Python questioned perhaps two sparrows carried the coconut?

Thanks for the link, Coach! Looks like a lot of good info.

I think I've got it figured; I'll use dual outflows. One with the bottom fed SLO in too small, at 2" (50.9 mm.) This may cause over filling of the FT. So at around 8" (203 mm) above the SLO I'll have a 4" (101 mm) outflow possibly as a pond skimmer