Backyard Aquaponics
A place to discuss aquaponics

arbe

I have a 90mm SLO all the way from the tank and as a backbone which I then handoff and reduce to 25mm for my 3 grow beds and blue barrel filter.

4500 lph pump with about 80cm of head.

The backbone almost gets completely filled to the top so I guess I could supply a couple more grow beds before I guess I will need a more powerful pump so I can supply even more beds. :think:

DrLuke

I had 2x40mm slo and they could barely clear water at the rate I desired for my 3000lt/h pump at 1m head. I.e there's was no room for adjusting flow to individual beds. Had to put an additional 40mm overflow in aswell. It is doing the job with all three.

bunson

Balance the inflow with the outflow and you'll figure out what diameter of SLO is actually required, and it's useful in a lot of situations as well!

Simple version: (imperial)
http://www.performancepropumps.com/PDF_Files/FrictionLossChart.pdf

More technical: (metric)
http://www.vinidex.com.au/files/technical_notes/Flowcharts/20101220_vin015_pvc_flow_charts.pdf

Scott

[edit] I thought this website was offline, but then clicked it again and voila, there it was, a REALLY handy reference for all things piping! http://www.duralirrigation.com.au/uploads/documents/Hunter-irrigation-handbook.pdf

Stuart Chignell

An easier way to do is to keep the velocity in the drain/slo/overflow whatever to less than 0.75m/s but more than 0.6m/s. At these speeds the head required to operate them is around 5cm-7cm (ie the water level in the tank will be about 5-7cm over the drain) At around 1m/s the required head gets to be over 10cm and increases exponentially as the water velocity increases. Any lower and you may have solids settling in your drain.

If you want technical then the vinidex manual doesn't cut it in my opinion. Perry's Chemical Engineers' Handbook on the other hand is excellent. Chapter 6 deals with fluid dynamics.

MacGyver

Are 90mm rain water down pipes okay to use?

Stuart Chignell

Do a search for safe and PVC and you will get a lot of opinions.

I would not use it but I would use DWV that didn't have the foamed core.

MacGyver

Does DWV stand for Drain Waste Vent system? This would be better suited?

Is this type of piping available from Bunnings?

Stuart Chignell

That is right but the stuff you get from Bunnings is the really cheap nasty stuff with the foamed core. If you establish a relationship with you pluming supply you should be able to get things cheaper there than you will at bunnings and it should be a better product as well.

bunson

If you're going to use DWV in your system, then it should be used all the way through your system (or at least in the entirety of individual sections) 90mm pressure PVC (like used in reticulation) is not the same diameter as 90mm DWV; all the fittings are different too and unless you manufacture something really sexy, it is almost impossible to mix types and fittings.

Stuart Chignell

If you are going to be using any sizes above 90 then make it all dwv cheaper than pressure stronger than storm. Pressure pipe has always seemed to me to be an extra expense in $ and enviro foot print that was not warranted.

MacGyver

If the SLO is 90mm then would that mean that a stand pipe in the grow bed should also be 90mm to cope with the incoming flow and avoid an overflow in the grow bed? (That's if there is only one grow bed) Multiple grow beds would allow for the flow coming from the SLO to be split but if you only have one grow bed should the stand pipe also be 90mm?

arbe

I wouldn't think so. I have a 90mm SLO and 3 beds, each with only 20mm stand pipes installed.

If the bed was going to over flow it would almost create a siphon which would move more water than a gravity fed SLO could deliver.

I say almost as when I have run my beds as constant flood and the SLO is delivering too much water the standpipe tries to siphon but keeps breaking sucking air at the top making a loud gurgling noise. The water level in the grow bed gets a little height than 'normal' but there is no way the growbed will over flow.

MacGyver

Okay thanks Arbe!

MacGyver

Is it possible to make a SLO without having to make a hole in the side of a tank?

Charlie

Nup

It has to overflow, if the SLO was above the FT level.... well the water would overflow onto the ground before it could go through the SLO.

You know this McGyver :dontknow:

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Backyard Aquaponics
A place to discuss aquaponics