Backyard Aquaponics
A place to discuss aquaponics

You should be able to feed the water in with or without a pump although you might have to regulate how much water flows to the RFF if your pump is too strong.

Radial Flow Filters are designed to remove settleable solids. Particle size isn't as important as it's settleability, some large particles will never settle and some small ones will. They just don't work the way something like a Drum Filter or Static Upflow Filter would where only certain sized particles can pass through, although, you can have some effect on what settles by adjusting the retention time which gets back to regulating the flow coming into the RFF.

Thanks Scotty

Pumping into an RFF instead of using a gravity flow should work just fine, so long as it's set up right - i.e. the inflow is pointed up as per usual and is a nice wide pipe (a narrow pipe will make your RFF into a turbulent fountain, which would probably look cool but not work ), the flow rate and size of the RFF combine to give you a suitable dwell time, etc.

Thanks Mel.
Will play around with design and flow rate

Gday all,
good idea to start with .the problem i see is how do you hold the bottom of the radial filter in position you may encounter a build up of soilds at that point that may be very hard too clean out...
with the filter in the sub tank will it be possible to remove all solids from the filter if not small/large particles will endd up in the growbeds

Is there a reason that I should have the pipe from the FT turn and go down, entering the RFF near the bottom, instead of going straight across into the RFF around midway of the RFF?
Also, the pipe coming from the FT going up inside the RFF, does that need to be near the top of the baffle?

As long as the pipe from the FT is going in under the edge of the baffle there's no reason to drop it further before turning it upwards, unless you need to drop the pipe to get a nice gentle curve going up; two 45 degree elbows is better than one 90 degree elbow to have the water flowing in smoothly. Even then I'm pretty sure someone on this forum built an RFF where the inlet pipe goes through the baffle, though I don't remember if they ever posted about how well it worked.

The height of the end of the pipe is determined more by the height of the outlet - it should be lower than the outlet, so the water isn't 'fountaining' at all. Your baffle might come up much higher than that depending on how you suspend it in the barrel (mine does).

Thanks Mel.

Have finished building my RFF.


The Flow rate of the RFF is about 2 Litres/min, and is made from a 200litre barrel and 8litre bucket inside.
and has a retention time of about 1hr and 40mins. So plenty of time for solids to settle out...I hope.

From the RFF it flows into my DWC trough which is about 300 litres with the same flow rate of 2L/m, so that gives it a retention time of about 2 1/2hrs, and from what I've read, DWC rentention time should be between 1 and 4hrs, so I'm good...I hope.

Hope to plant some letttuce and maybe herbs this week and see how it all goes.

Comments/criticisms about the this set up would be appreciated.

Looks good and from and what I can see it should work . If you have troubles with the plants in the DWC it will likely be from fine suspended solids sticking to the roots. If you find that this happens then you'll need to add a fines filter and probably the easiest would be a small Static Upflow Filter.

Thanks Scotty.
I did a quick google for Static Upflow Filter but kept finding RFF.
Is that basically a filter with water entering at the bottom, rising through a media such as an onion bag filled with bottle tops, then flowing out the top?

Well I haven't seen the onion bag bit but basically that is correct. The water comes in from below and rises up through floating media to an outlet. Solids are trapped within and beneath the floating media. The onion bags in my opinion would make it harder to clean the media. I've heard of people doing this with aquarium systems and things like scrubbies. Usually to clean a SUF, with the flow stopped you can either aerate or stir some other way to release the solids and drain them away. You don't need matala or anything else in there - just covers on the pipes to prevent losing any of the media.

The particle size that is filtered can be adjusted mainly by increasing or decreasing media size and/or media layer thickness. Flow rate also affects retention - if it's too fast channels open where larger solids can pass without being filtered out.

Bottle caps and many other floating plastics could be used, just try to pick something that's safe.

It doesn't have to be fancy but for a really *sigh* example, the Nexus Eazy Pod or Eazy Pod 2 are a pretty neat combination filter with a center section that is a Static Upflow Filter. The outer area is a vortex filter. Like most of these filters (including a basic SUF) it does some biofiltration and they advertise it as such. Cleaning is done by aeration. Here's a video that shows the vortex action - https://www.youtube.com/watch?v=fUagSn5QOM4. Here's one that shows cleaning and at the beginning and end how the media is static in the center section - https://www.youtube.com/watch?v=D8u19l1m2HQ. It's a pretty neat setup but expensive.

Thanks again.
I was thinking of using the onion bag with the bottle tops in it, so as to stop the bottle tops accidentally getting in the outflow pipe, and when ready to clean, just take out the onion bag, rinse off with a hose and put back in.

That RFF should be pretty darn awesome, Farmz! Mine has a dwell time of about five minutes and does a great job.

The onion bag idea should work fine as long as it doesn't cause any gaps between the bagful of media and the edge of whatever container you're using for your filter; if the water can go around instead of through, it will. The other way to stop the media getting into the outflow pipe is to make the outflow a length of pipe with a cap on the end, with holes and/or slots in the pipe and cap that water can get into but that are too small to let the media in (in which case you can't pull the media out in one bag to hose it off, but can clean the way Scotty suggested).

Thanks Mel.
I'm hoping the RFF is sufficient. Will find out shortly as I planted 42 lettuce seedlings this afternoon