Backyard Aquaponics
A place to discuss aquaponics

Soz dude, but thats not quite right as far as i know.

RFF is NOT about slowing, it is about "throwing" the particles out of suspension, so infact instead of wanting the water to be as slow as possible and slow even more as a settling tank ( i know people say it is about the fact that the dwater moving up moves slowly), There is a minimum speed which RFFs have to operate at, as my understanding goes, you need the "upturn" of water to be at a decent rate for the soilds to be "thrown" as i said, not simply settle.

I think that you will find that even Stuart would agree, as I am confident that in a design thread he spoke of them working on slowing.. I quote ""A RFF works on reducing water velocity to allow settling.""
and then he says ""A swirl filter works on having a rotating current and using the centrifugal forces to separate the solids from the main flow and then allowing them to settle.""
Indeed, my gravity and this happens - YES - when it slows

I am more than happy to disagree with the proposition that RFF and SWIRL are significantly different, and that they work on different principals..

IMHO - They both work the same by allowing the water to slow and the solids precipitate out of suspension, and folk can use whatever mechanical description they wish to describe that.. :-)
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Paul says the opposite.

I have read elsewhere that it is the turn in the water, not the slowing as it rises, you can also stand there and watch the solids get thrown out of suspension, they do not make it past the turn, they dont make it into the "slow water" to then settle.

I personally would trust stus maths over pauls, but pauls knowlegde of equipment over stus.

http://www.backyardaquaponics.com/forum/viewtopic.php?f=8&t=25521&start=15
""A RFF works on reducing water velocity to allow settling. A swirl filter works on having a rotating current and using the centrifugal forces to separate the solids from the main flow and then allowing them to settle.""

I can't help what I understand and Stuart said

ALLOWING is not a scientific term, but SLOWING sure is




Simply LOOK at the claimed great RFF design - that fig 3 on page 53.
Water enters a collar at the top of the tank.. Water can ONLY flow down the tube as I understand it extends above the water level.
That water sinks down and then flows back up around the outside of the tube..
The outside size is 1.52M diameter.. the suspended a 0.61M tube over the inlet..
Now I ain't much good at maths any more, but I suggest that the inflow pipe is again 0.61 and thus the area 0.29SqM
Now the total cylinder is 1.52M and thus the area 1.8SqM
and the inflow is thus 0.29SqM and the outflow is 1.8-0.29 = 1.51SqM
So there is a 5:1 increase in flow cross section and thus a 5:1 reduction in VELOCITY
and that equals SLOWING by any explanation.. or terminology

I could only suggest that what YOU are seeing, IS the same thing.. the solids falling from the faster flow as it "SLOWS".. and not this notion of being "Thrown" down - That is only an uneducated explanation..

A swirl filter does exactly the same thing, swirling the inlet around the wall and you could also suggest there was an invisible collar, where the water at the wall is the fastest moving and at the center, the slowest..
Being forced in at the top, the only direction the swirling water can go is down the inside of the container and the deep it goes the more energy that is lost and solids "Fall Out" and the water drifts into the middle and up and out the top..

So once again, it releases solids by slowing down..

EXACTLY the SAME.. just different means

Sorry - I don't want to start fights, over who has the best knowledge base, and I am not standing as an expert, which by definition , is an unknown drip under pressure..
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Nah, unfortunetaly all the maths wont help in this case, the principal comes from the collar, the width of the outer container is pretty irrelevant unless it is too small.
The flow rate vs. collar size is what matters, you need enough speed flowing downwards and a sharp enough turn back upwards to allow the solids to no longer follow the flow of the water, but to keep the same trajectory until they hit a slow enough spot to not rise.

If it was simply a settling tank which works on slowing like you suggest then you wouldnt need the collar.

Believe what you want.. or what you have been told..
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For the cost of that fitting, I'd rather get this instead:
http://www.ebay.com/itm/Ace-Roto-Mold-15-Gallon-Full-Drain-Inductor-Tank-INFD15-19-/251845935774?pt=LH_DefaultDomain_0&hash=item3aa330029e

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literally exact same.

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I wish they were available in Oz..

especially the 60Gal one = Plenty capacity to upsize
(but I would not be sure if it would take the weight on those legs- cant really tell how built)
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