Backyard Aquaponics
A place to discuss aquaponics

Once again coach this is not a members system it is hardware...........
However, as these float I'm not sure they would work as a sand substitute. One of the sites I work at has a blow mould company there and they use small polyethylene beads (around 1/4")in their process which I think would be ideal for what you require.

Its my system, I'm a member...therefore: member's system.
Sorry, didn't think it was a huge deal whet it was headed under. Just trying to get some feedback. Scotty usually moves thing I post incorrectly anyways. So, no worries. Thanks for the suggestion on the plastic beads. They float also, so not sure if they are better, or just more expensive??

Been there, done that

Shitloads better and just float.

..
IMHO... take a.zillion small floating beads and suspend them in a nutrient flow..
So where will the bacteria be .. on the surface of the bead and what is that bead doing if not rubbing against its neighbours .... rubbing the bacteria off..

Proof... did I post that image of a new extrusion... where is the bacteria.. on all inside surfaces and NONE. On the outside..

So how will a zillion round beads perform, if not dismally..
http://www.backyardaquaponics.com/forum/viewtopic.php?f=1&t=25475&start=15
..
.

My understanding, and I could be wrong is that unless you are aerating, the media is packed in a bed with these bead filters. It's not like an MBBR where the media is turning over, it's more like a static media bed, this is why it works for trapping solids. If you don't clean it frequently then you run into troubles with getting anaerobic areas - having said this his unit will be after some other filtration so if there isn't much solids accumulation, he might not need to flush it that often. When you back wash the beads, then you will get the cleaning of the outside of the beads and I think you can overdo this. Personally I like the wagon wheel style media like k1 for things like this but it's what I've used . I don't know if this type of media really helps as much with the packed beds that aren't tumbling. Seems like with beads you could only get a limited number of places touching, just like putting marbles side by side.

..
PS.. polystyrene beads.. not sure that I would like them.. they would FLOAT massively, and you would firstly have an issue controlling them.. and..
I would think that they would float, within their containment and crust the beads are the top.. possibly,making them impermiable to water flow..

I would also worrie about the possibility of chemical leaching from such an exposed area.. folk even seem to wonder about PS sheeting and possible chemicals ..

The PE beads would be more structurally stable and chemically.. IMHO

I have wondered if recycling depots actually separate drink bottle caps (eg coke tops from pet bottles) as they could make for a cheap media.. not efficient.. but cheap..
..
.

I think there have been some problems with the beads clumping and things like that but I don't know how common they are and I suspect that the more often you back wash the less likely this is to happen.

As far as the leaching, I'm not saying throw caution to the wind but there is very little solid material to leach from with foam. I do think it's something to be concerned with and I'd probably go with the polyethylene beads but using the polystyrene wouldn't throw me off too much just look where it came from and how it was made (fire retardants, etc...).

Chris

Is the purpose for filtration or biofiltration?
Polystyrene is used in microbead filters and I don't think suitable for our application. Polyethelene beads are more durable if you upflow it will require attention to clogging if you downflow you loose (to a degree) the mechanical filtration but retain the biological filtration.

Bui as far as I am aware with a moving bed filter collisions would remove excess biofilm.
Bottlecaps are removed as they are usually recycle code 2 PET is recycle code one and I do use them as grow media and have used them as biofilter media.

My assumption would be that collisions would remove MOST of the bacteria ??? 99% most

Just think how these gather the bacteria and how different it would be if smooth and round..


so that would suggest value in contacting recycling depots..
I bet they would be delighted to sell them at above re-cycle value..

Peter

Peter

I don't think they loose the bacteria only the excess bioslime.

If you go to a recycling depot see if you can get rejected (as in new but faulty) bottlecaps and not with paper or foil inserts. Btw they dont move as easily as smaller bio media.

David