Backyard Aquaponics
A place to discuss aquaponics

Just kicking around the idea of an underwater bio filter. PVC or a section of blue drum with mesh on both sides. Inside are bio balls and air stones. The idea being for systems without enough GB's or with an amount of water that can't be pumped through GB's every hr.eg 20kl and larger systems.

I would have thought this would be a waste of tank space. If additional biofiltration is necessary, it is easy enough to rig something up outside of the tank and is also easier to ensure oxygen supply to the bacteria that way.

I would like to try a liner of some biofilter material, maybe even a "wall" of gravel around the outside perimeter of the tank. Wouldn't take up too much space if it isn't too thick, but would still give some additional filter volume.

Dufflight

I used an inpond biofilter as an intake for my pump, bout the size of a 10 litre paint tin. No extra air it relies on my pump flowing water through it. Only advantage I have found is that it stops fish and large lumps of material being sucked into the intake.

Just thinking of an easy way of getting 55kl of water through a filter per hr. An air lift at zero head running off existing air supply would pass a lot of water through a filter material. If the bacteria would live there is another question.

Are you trying to get rid of crap or just doing the NH-NO thing?
The whole surface of your FT has the bacteria on it without putting anything in there.

Duff you might like to check out the yahoo swimming-ponds group (sucks that you have to sign up to access info) - these use an underwater gravel-filter - layer of gravel on the base of the pool with water drawn down through it.

There are pics. etc of how to set them up - might give you some ideas?

Just looking at the converting of ammonia and nitrite.
Have converted the protein skimmer as a test run. Does move a lot of water. A deeper air stone would increase the amount of water moved.
http://www.youtube.com/watch?v=HbXA0tFPAnc

So your basically just impatient with the cycling thing

Finally someone understands me.
The pool has been running for over a month with the GB's. Been adding the ammonia and have had 80 yabbies and then 6 goldies before adding the silvers. There are nitrate readings so it has cycled. But the bacteria is not got big enough to handle the amount in the system. Now if you have to have all of the water go through the GB's every hour then thats a lot of pumping. 55000ltrs an hr. If in a week everything drops to 0 then alls well. But if the volume of water is a problem then I would like to find another way of handling the nitrite problem.

duff, if EVERYTHING drops to zero then no amount of biofilter is going to provide NO3

Wasn't even thinking of the No3. Just the ones that can kill the fishies.

took a look at your video, Dufflight
nice video
but I don't see a lot of water moving
what I see is a lot of bubbles with a little water

frank

Knew you were going to post that even as I was filming. Even though of sitting a 20ltr bucket next to it and timing how long the bubbles take to fill it. If I get time I will time it so you can work out the math. This was just a test run. If it is something that is worth while for larger tanks then it will be a lot bigger. But you will be happy to know it is not costing anything to run this experiment as the air blower runs all the time anyway.

my mistake, duff, carry on