Backyard Aquaponics
A place to discuss aquaponics

nah stick to how you are thinking if space is limited, you will most likely just have to flush your dwc bed sometimes.


there is no good reason to have the outlet of the the RFF low in the barrel, it can be cut out anywhere at or lower than the desired water level in the RFF.

thanks Mel Redcap.
The SLO on the FT is at the top of the tank, so no room to have the RFF inlet higher.
Bummer, that really limits my options of what to build the RFF out of, as the FT is about 760mm tall, with a 2650lph pump.
So by my math, to get a 2 minute standing time in the RFF I need a container of about 85-90Ltrs.

Ok thanks.
and the desired water level in the RFF is dictated by the water level in the FT?

Well, if the container you want to build your RFF out of is taller than your FT, that's still fine - you just won't be using all the available height. I'm using 200L barrels that are about 1m tall for my filters; if you got one of those, you could just put all the fittings lower in it and as long as you were using at least half of its height you'd have enough water in there to get a good dwell time. Or if it was inconvenient to work around, you could cut the top off. And if you find a nice wide container that's too short, you can just put it up on bricks.

Your desired water level is going to have to be lower than the FT water level, and higher than the growbed it's flowing on to. So if the top edge of your growbed is 60cm high, and your outlet from the RFF goes over its edge, a water level in the RFF of about 65cm would give you a drop from the FT and then a drop to the growbed, letting gravity do its job for you.

not really, it will always be lower than the FT level since each step has to be lower in a gravity fed system, but basically you have the outlet (and water level) as high or as low as you want.... as long as its lower than the inlet. maximising the amount of water in the RFF is the way to go though, so outlet just a little lower than inlet.

as mel said, 200l barrels (blue barrel, black pickle barrel, etc) work well as RFFs, i use a black pickle/olive barrel.

and think I read somewhere that the rule of thumb for make the baffle is the depth is equal to one third of the depth of the RFF, and one third the width of the diameter.
So if the height of the RFF is 760mm tall with a diameter of 490mm, then the baffle should be about 250mm deep by 163mm diameter.
Is that correct??

Yep, that sounds right! If you're having trouble finding something the right diameter, go a bit larger.

Thanks.
Was wondering about that.

Does the RFF have to be round?
Was thinking of maybe a rectangular storage tote.

The actual tank/container should be fine any shape, but the cone around the intake should probably be round (although even then I guess that wouldn't matter much either.)

Thanks.

Hello, I think you have a nice looking build there. You can see the craftsmanship that went into it. I have a few question for you.

1) How do you empty it?

2) How often do you empty it?

3) How long does it take to clean it out?

4) What is your estimated flow rate?

I'm thinking about adding something like that on one of my builds here in Palm harbor, Florida.

Regards,
Daniel Jerome
Palm Harbor, Florida

Ok. Think I've got the materials needed for my RFF.
Going to try and do a Fines Filter. Are there any rules of thumb for making a fines filter, like required volume of container, flow rates ect?
I was thinking same flow rate as the RFF?

Some use cloth or nets as a fines filter. I've used both and cleaning them is a messy pain in the butt. I have just recently switched my net tank to a Static Upflow with k2 media. I plumbed in a bypass loop to keep the water flow on while cleaning a filter. Takes all but 5 min to clean or less, and I never touched the water. These static up flows I was told can handle high volumes. I'm running 5-800 GPH without issue.

Each static filter has 4 cu ft of k2.

Ok.
Thanks for the advice.
k2! Pricey isn't it?