Backyard Aquaponics
A place to discuss aquaponics

UPDATE: I think I just came up with something better. A bag filter like this http://www.aquaticeco.com/subcategories/3102/Mesh-Filter-Bags or this http://www.aquaticeco.com/subcategories/1480/Polyester-Mesh-Bags Fixed to the OD of a PVC pipe in that same barrel that I had planned up for the screens.

I dont like the bag idea.
ive tried to use a home made "bag" style filter using cloth, to try filter my scoria dust out.
it was a massive failure.
it started well, but when the walls started to get lined with gunk, it started to back up and the whole bag became full of water that couldnt escape, it started flowing back out of the bag.

with your much lower water rate, it may work fine, but like the screen, once there is a thin film on it, the water wil try to find another way to go - not a probem with pressured tanks, but im sure your not doing a pressure filter.

Do you know about how many microns it was? Did you clean it often? How large was it? Did you have a RFF or large solid removal device upstream of it? I think that dust may be fundamentally different and more abundant than <100 micron fish waste



I was planning to build it into a 5 gallon barrel so that if it were to get clogged and overflow, it would just bypass the filter. I figure it'll work just like a mat filter or screen but the water will have much much more surface area to escape through. Bioslime is my concern though.

it was for dust, so no RFF, etc wouldnt have helped.
it is hard to say the microns, it was just made out of fabric i had around.
the weave was fairly sparce though, it wasnt like suit material or anything.
as far as cleaning goes, i did clean it once fairly quicky and it seemed to do nothing, a few hours later it was already too late. it was a large bag (held prob. 30-40 litres) so i coudnt pull it out of my sump, so i couldnt clean it the second time.

Im sure this thing wont be as bad as mine though.

Sounds like it collected a lot of dust! You probably had pounds and pounds of dust to clear out. I really think comparing that suspended solids after RFF treatment is apples and oranges.

I made a quick sketch for you:



Drawing kind of sucks but you can see that the bag is suspended within a large diameter pipe with a reducer to support the mouth of the bag. Lots of holes in the pipe to let water out into the main chamber. If the bag becomes impassable, the water just flows out the top. I may have to put the outlet pipe at the bottom, not sure.

That looks like a better design.
little things can make a difference.


I didnt end up getting anything at all out with my filter, it clogged too quickly. - there was atleast a 25l bucket worth on the bottom when i pulled that bed apart months later.
as you said, you will be sending much less to it.

I think it has to go like this:



The equalization of the pressure on both sides of the filter bag due to the output being so high in that first diagram would be no bueno.

You may get half a day out of your bag if your lucky. I once tried a soakwell sock in a 44g barrel, a total and utter failure and that was a big bag.

Damnit! Can you tell me about your methods? Was it after a RFF? How did the flow work? I wonder how people tackle this issue...

mostly the issue is sorted with a normal growbed between RFF and DWC around here.

I wonder if that's how they handle it commercially too? Perhaps they use sieve or drum filters?

No it was one of my stupider ideas where I pumped straight from the pond back into the pond. I thought the large surface area would be able to handle the relatively small flow, about 2000lph.

With filtration on AP systems its not like just smack a cartridge in the flow line (unless you have an awful lot) you have to get the particles to clump or stick to something, or both. There was a diagram on the previous page of an upflow bead filter, they work quite well. In fact if you had lots of money you could upflow through Kaldnes with a slow flow and just knock the crap off it on a regular basis (think beads are better though).

Edit

I am surprised no one has improved the efficiency of an RFF by putting something in the way of the outward flow to create this effect.

Okay well that kind of gives me hope tbh. I'll be taking out the big solids with a RFF first. Plus I think my body of water and number of fish will be far far less than yours. 120 gallons (450 liters) for the fish tank.

How big are your fishies? How much water do you have in that pond?



I'll check um out!

About 7-8 kl free water, 800l bottlecaps in a spa running Constant flood, 200l bottlecaps in pots running constant flow, a 40-60l useless (well fairly usless) mechanical filter.
Unknown number of goldfish of various sizes (a lot are black) and unknown number of gilgies.

Sounds like an awesome setup! Not quiiiite the same scale as mine though . Mine is 17x smaller than yours. Even with a 44g filter, that's only 1:52 of your volume ratio. Plus I'm willing to bet that you had a fair bit of suspended solids ready to jump into that filter bag as soon as you gave them a chance. If you ran that bag for a while I bet that you'd start getting a bit more time in between filter bag changes. I could be 1000% wrong though.