Backyard Aquaponics
A place to discuss aquaponics

Hi All

I'm finally getting close to cycling

But I think I have oversized my pump
Here my setup first off
I have 2 IBC fish tanks connected into a single Radial Flow Filter 1-1/2 in PVC
I have Radial Flow Filter connected to Bio Filter 1-1/2 in PVC
I have the Bio Filter connected to the sump tank 1-1/2 in PVC

The Sump Tank Splits the between Growing and back to the two fish tanks. 1 in PVC

Growing is all 1 in PVC Sump Tank Feeds to NFT and DWC beds

NFT and DWC beds drain into secondary tank which is pumped back into either
the Sump Tank or either fish tank.

Here are my problems (I think)

1) When I run the Sump Pump just on the fish tank loop. The Pump Will fill the fish tanks to overflowing.
Basically the water coming into the two fish tanks is greater than the water exiting the two fish tanks into the Radial Filter.


2) When I run the Sump Pump to the growing loop only. The Pump works but it sounds like it's under pressure
Starts off fine then begins to whine. Like it is capable of providing more water, but the lines are not using up the water fast enough.


I will run the sump pump so that water flows to both growing and fish tanks. But Two questions that are plaguing me.

How can I measure the flow rate into the fish tanks, and how can I measure the flow rate out of the fish tanks?

Secondly, How can I solve the issue that water coming into the fish tanks is faster than water exiting the fish tanks?


Thanks in advance


Any ideas how to address these two problems

Here are the pictures with notes saying what is what

To measure the flow rate into the fish tanks just use a gallon jug and a watch with a second hand. See how long it takes to fill the jug at the fish tank spigot and then calculate flow based on that (you'll have to convert to GPM or GPH or whatever units you want). I'm not sure on measuring the flow out of the tanks.

Most people put a T with a ball valve to regulate the flow in the pipe leaving the pump so that they can use any excess flow to aerate the sump or fish tank (depending on where the pump is located). You sort of have that with pipe F but I don't see a valve and most people put the T on the pipe as it's coming up from the pump. You can use that valve to reduce the flow going into the fish tank and hopefully prevent backup.

Thanks scotty435

I did't have a valve at the time of the photo, but have added one to (F) Mainly because without it I'm not getting enough water at the grow area. This way I now get enough water and use the (F) valve to take the back pressure off of the pump



FYI for all following I did some measurements ::


This raise a question, How can I increase the Fish OUT flow rate ?
at 126 GPH and a 275 gallon IBC Tote implies water exchange of 2.18 Hours or 2 hrs 11 mins or every 2 Hours Plus

I think that I read somewhere, you need to exchange water at every hour or 90 minutes (1:30) to keep fish healthy ???

Secondly, (which I'm guessing is related to first question) How do you increase the "vacuum" suction on the SLO to draw more (or faster) solids from the bottom of the fish tank ?


Any ideas

Thanks in advance

Just curious how much of a seal does the radial flow filter lid need ?

I keeping having the thought/idea that pressure has built up inside the radial flow filter pushing back the water back up into the SLO and thus the fish tank.

The bucket which is bolted/suspended from the lid into the radial flow filter surrounding the inlet pipe. Had NO holes near the lid thus it took force to push the lid down. Having drilled a few holes (seeing this on a photo somewhere) the pressure is less.

Thanks in advance

Connecting the hose to either end would mess up your flow rates unless it was the same size as the pipe you were connecting to.

You don't need a seal on the RFF lid or even a lid except to place the center bucket where it needs to be.

Might be back pressure from media blocking the outflow of the biofilter depending on how it's designed.

126GPH seems extyremely slow for a 1.5" SLO. That's under 500lph or ~8lpm. My dual 50mm (<2") SLOs handle over 170lpm, or 85lpm each- about 10X as much for only slightly larger size.
Are the holes in the FT end of the SLO too small, or too few in number?

Restricting the pump flow with a tap into the FT to ease any overflow problems is not a problem for the pump- more back pressure is EXACTLY the same as pumping to a higher head as far as the pump is concerned- the flow rate is reduced. Most pumps use less energy at lower flow rates.

on the country probably too big These strainer are at the bottom of the SLO

my gut reaction is that there is something slowing it down
It seems a bit better to the naked eye with the holes in the bucket near the lid (inside the radial flow filter) and with the lid of the radial flow filter propped up so that there is no seal on the radial flow lid at all.

So far all appears well the water level is remaining constant in the fish tanks. The water is flowing through the growing beds, and into the fish tank.

On the one hand I wish it was faster into the fish tanks so that the venturi would work better. But if they go any faster it overflows the fish tank since the SLO is not draining fast enough.

For now It will work while I start the cycling process. But I may end up replumbing the the 1-1/2" SLO to 2"

Thanks all