Backyard Aquaponics
A place to discuss aquaponics

That tank always seems to stay nice and clear. The 1" slo was a little to slow, but the tank never overflowed. But I knew when I added more grow beds it would not be enough. I am going to have probably 20 grow beds dumping into that single IBC soon.

I just make a sum to convert my fish tank to constant height and accommodate more GBs. I can't find any uniseal so I use an 50mm rubber pan cone that fit perfectly for 40mm pipe. I use 40mm SLO because all my plumbing is using 32mm for water distrbution & 40mm for draining. It makes things more simple. The small size pipe makes better solid lift whereas the bigger size reduce tank level fluctuation. If thing didn't work out well, I will cap the T (or use elbow) and drill a hole about 10cm below the elbow to increase flow rate.

Cheers,
Long.

I plan on using 3" myself. Over here in the U.S. 90mm/3.5" is very rare if it is available at all (I've never seen it); maybe it's available at a specialty plumbing shop at a high price.

So your real choices are 3" or 4", and like helomech said 3" should be plenty big enough for IBC-based systems.

I know what you are talking about helo

I decided to finally go with a slo, but being a "do it and see" person could cost me a tad too much in this scenario so I'm looking for help..again
My first question that could do away with any others is how to calculate the flow rate through a 2" slo out of 900 gallon tank that's being filled by a 700gph pump? Does the size of the tank even matter for such a calculation?

I thought I used to know what a slo was and exactly how they worked but i may be a little lost there as well. Its apparently not a siphon yet you guys seem to be installing them to "suck"...like a siphon.

This will be somewhat of a chop system...FT/GB/ST/DWC (rafts) The sump will overflow into 2 DWC beds (4'x30') and pumped back to FT.

Any help is welcomed/needed

Nope, the tank size doesn't matter. If it is a 700GPH pump then 700GPH will be flowing through the SLO. 2" PVC is rated for 3300 gph for gravity flow (that doesn't count any 90s or other flow restrictions though).

The SLO works because the water level in the tank rises higher than the SLO outlet and that water pressure forces water into the SLO inlet at the bottom of your tank up and out the SLO outlet (if that makes sense lol). It is very similar to a siphon and would work as one if you didn't put the T in place at the top.

Wow..3300gph via gravity!! That answers a lot for me right there! However, that really makes me scratch my head when I read about 90mm or other large slo's.
Thanks for that info but I fail to grasp your description of a slo..hahaha. I can be a little slow to pick up the simplicity of certain things and these systems really do a number on me...and my self esteem
Its difficult for me to grasp how such a large hole, what is essentially a drain hole, would have any sort of suction when I'm assuming that only maybe 25% of that hole is filled with water while its draining. Do I need to replace the word suction with a better term?

Would I be too far off base to say that a slo is a siphon that never quite fires completely? ...or stops completely??


I apologize for my ignorance but please bare with me and know that I'm from Arkansas I'll get there...

The vertical pipe is what really does the lifting in the SLO, and it will be 100% full all the time, the horizontal exit won't be very full but it doesn't need to be to carry stuff sideways and out.

This poorly drawn MS Paint image might help:



As the (dark blue) water level rises over the level of the SLO's exit from the FT, it creates a pressure to equalize the water level in the FT and the inside of the SLO.
This creates a suction as water is drawn up the SLO vertical pipe. Since water keeps coming into your FT from your pump this process never stops and water leaves through your SLO since there is a way out.


Without the T at the top of the vertical pipe the SLO would be a siphon, yes.

Thanks again..thats about how I picture it. I'll be installing one next week so I'll get to see the magic in person ..hahaha

Lowcarb's got some mad paint skills!

Yes, he seems to be quite gifted

Valedictorian in my art college rofl

I went with a 3inch slo instead of a 2 and installed it with a uniseal. I somehow managed to accomplish such a feat by myself which turned in to quite a lengthy cursing match. It wouldn't have been as difficult if I were left handed but the way my beds were it was impossible to get to the slo from the other side.

I've never read that its difficult to push a 3" pipe through a 2 3/4 hole so consider yourselves warned

It doesn't seem to have any suction that I was imagining in my head but its working.

A tip for next time when pushing a 90mm pipe through a uniseal (care of Tclynx) is to attach a T piece to the end and push on that rather than the open end of the pipe.

Wish I knew that before I installed 7 of them in my system.

Thanks arbe, a tee may have helped a bit but it wasn't the edge of the pvc that had me going. Iit was just the strength needed to push and wiggle a 5ft piece of pipe with one hand while the other hand is inside the tank trying to keep it from collapsing. It was just how I had to position myself to have a go at it...physics was not on my side.

Imagine trying to snap a 5ft long 2"x2" board by just squeezing the ends toward each other...that's what it felt like to me. I strained something in my left arm behind my elbow and the bicep is visually bruised just below the shoulder.
Young at heart but the rest of me doesn't agree


I'll have to check out your system cause I can't visualize why a system would need 7!!!