Backyard Aquaponics
A place to discuss aquaponics

While I find this thread most amusing I would point out that there seems to be a little confusion ie. "I never said swirls don't work, I said they don't work as well as a RFF and they do require a higher hydraulic head which does require more energy."
Sorry Stuart but there is a difference between a device which requires a greater velocity to work and I think this is not it.
Both require a longer path to allow the heavy solids to settle. I very much doubt that centrifugal force is at work in a low velocity swirl filter.
On the upside a RFF is requiring a change in direction and as the water exits the central pipe velocity is reduced and the heavier particles would tend not to be lifted (this is actually quite a complex situation re flows and no doubt you, as in everyone, should err on the larger side).
As for low velocity swirls life gets more fun.

BTW this is only imho after a hard day at work and a few beers.

any idea where this formula for determining surface area based on flow resides ?

I would imagine mine would need to be 30x the surface area of most of the ones on youtube as they are made for 1000L IBC's ...

my flow is 31800L / hr, 530L / min, 9L a sec ...

I am currently trying to size up the pipes and container size I need

AFAK velocity should be 3.5 m/s if using 60mm pipe

*edit* found it plus an whitepaper
http://integrated-aqua.com/wordpress/wp ... epaper.pdf

200 LPM per M2

so I would need 3 sqm surface area( I think )

still trying to work out the retention time math i think they want you to hold it 30sec - 5 mins

so would that mean @ the minimum 30 sec I would need 265L container
and 2650L would be the largest I would need ?

shame IBC are 1.2sqm maybe stack 3x of them ? and split the flow between them ?

looks like I would need at least 1.8~2m diameter tank
possible but costly

I'm pretty sure the article on the design guidelines was posted earlier in this thread

I was a bit surprised to read up on the difference in efficieny to find RFF is roughly twice as good at removing solids.

Regarding the bit about where does the inlet pipe goes goes, I go this snippet from a paper called:
Solids removal from a coldwater recirculating system—comparison of a swirl separator and a radial-flow settler
by John Davidson, Steven T. Summerfelt
I don't have a link but it says it's available from ScienceDirect.com

Quote: "According to Metcalf and Eddy Inc. (1991), the design of the flow injection point within the
center of the radial-flow settler is critical to dampen the turbulence created by the flow
injection at the center of the tank. Therefore, the turbulence-dampening cylinder, located at
the center of the circular settling tank, should be designed with a minimum diameter that is
25% of the tank diameter and should be located well above the maximum depth of sludge to
minimize resuspension of the captured solids (Metcalf and Eddy Inc., 1991)."

So sounds like anything except the middle is going to give you less than optimal results. why bother then?

Poppa

That article either is the one I was talking about or is very similar to it.

Depending on how you install the outlet depends on where the optimal spot for the inlet is. Is commercial ones where the outlet is all around the outside then yes the center is the best spot. However, the difference is probably minimal and done more for our sensibilities than anything. The diameter and length of the baffle (turbulence dampening cylinder) is WAY more important.
For home made ones where the inlets and outlets tends to be in two spots (one spot each) then for optimal results they should be as far apart as possible but again the difference is probably minimal.