Backyard Aquaponics
A place to discuss aquaponics

Just because the pump connection is 32mm doesn't mean you are restricted to using 32mm pipe. If you were to you might find the flow cut by half or more.

Using 50mm pipe handling 2000Lph your velocity will be 0.34m/s there will be friction losses but it should be less than the 1m of head height that you have said that you have to play with.

Will look at the pump tomorrow and advise - im up for options from the master

Sooo - 50mm DWV on the grafity feed side to the grow beds - that work ok?

Thankyou

50mm DVW should be fine. I use 50mm DVW on both my 2,500L tanks then to RFF then twin 65mm DVW to the growbeds. I only have 150mm head over my grow beds so you are way better off.

One of my 50mm Sol`s has an air stone in it and it can draw down the tank water if I slow the pump down to much. I run 2,500 L/H to each tank.

I had thought about changing to 90mm but I am now quite happy with the 50mm DVW.

Thankyou Johny5

Since you have 1m of fall you have got lots of room to play with. You could calculate things out to design things to reduce the friction losses which would allow you to reduce the fall but if it you already have your structure in place and the fall set then there is no need to do that.

Depending on what pipe you run from the pump to the FTs there is a good chance that you will get more than 4000L/hr but there is a very good chance that you will get less if you use 32mm pipe.

I know you are still trying to figure things but how long is the run from the pump to the FT manifold (where the flows divide)?

Cheers Stuart

Re the outlets from the FT - DWV - looks like this will be fine at 50mm DWV then out to the GB's and into the DWC

Re the pressure side, the pump back to FT (where there is a manifold to split the return). There are 2 options, depending on which plan i do. its either about 10 metres or 5 metres. Should i be looking at 40 or 50mm PVC for pump back to FT?

The more i can get the better as i can bleed of excess via venturies etc, i know you can go bigger than the outlet but by how much?

Outlet Diameter: ¾", 1", 1 ¼", 1 ½" (19, 25, 32, 38 mm)

You can go as big as you like. The only reason not to go larger is that bigger pipes are more expensive and as you go larger the return (reduced friction losses) is less and less.

The friction losses from 10m of straight 32mm pipe is about 1.9m of head with a flow of 4000L/hr but to this you need to add the friction losses from all the bends, exit, valves, manifold, etc. (TDH = 1m + 1.9m + fitting losses=2.9m+fitting losses)

For 5m it is only about 1m of head loss (TDH=1m+0.9m+fitting losses).

This is the trick behind designing any system that is more complicated than just a couple of GBs, sump and FT. You have two layouts with different pump configurations. One suggests that you could use the cheaper 32mm pipe and not compromise your flow but that will make your drains more complicated and longer. It will also make them different which will likely mean that one will drain faster than the other which will certainly mean that one will produce different levels in the GBs, FT, RFF, Bio-filter or all of them. This may not be a problem certainly not an insurmountable one but it is something to think about.

Personally I try and keep my drains identical to avoid dealing with that issue but it is not always possible or even advisable. Like almost all things AP...it depends.

The fact that you have 1m of fall to play with gives you a lot of flexibility though.