Bio-Pellets - possible to use in a fluidized sand filter

[BigOldReef]

Hey Guys,

I hope this is the appropriate forum for my query. I have some friends that have been really pleased by adding bio-pellets to their system. So I thought I would try.

I am running a 5' tall fluidized sand filter with about 30lbs of ground glass media.

Can I add the bio-pellets to the fluidized sand filter ?

I have heard about people having issues with them clumping and the sand filter is 100% fluidized.

But I also know that the bacteria in the fluidized filter is exceptionally anaerobic... So will this affect the bacteria that the bio-pellets are supposedly culturing?

Thanks in advance for the sharing of your thoughts and experience.

Dave

[bertoni]

The bacteria in the sand filter and in the pellets probably are mostly aerobic. I don't know whether mixing the two is a very good idea. I'd expect the sand to abrade the pellets badly.

[Randy Holmes-Farley]

I agree I think it likely the sand will abrade the pellets.

[BigOldReef]

Bertoni, my experience and research with fluidized filters is that the bacteria is so concentrated that the oxygen becomes depleted in the fluidized reactor. In commercial applications a fluidized filter is usually followed by an ammonia tower to aerate the water coming out of the fluidized.

As for the sand abrading the pellets, the sand (ground glass) is fully fluidized, not just tumbling, so I would think friction against the two would be neglible. I know in some commercial fluidized filters they use coral sand, rather than the ground glass, and I have witnessed some of these filters that have run for 10+ years without the media grinding itself down.

[bertoni]

That's interesting. I'll have to see whether anyone's checked the pellet reactor output. I would have thought that anaerobic processes wouldn't be common in the pellets, but I could be wrong.

[Randy Holmes-Farley]

One line of thinking is that the formed biofilm in normal use of these pellets can get thick enough to become hypoxic on the pellet surface.

That may or may not be possible with glass beads continually bumping around on it.

[Plato]

A bio pellet reactor uses the same principles as a fluidized sand filter. The media instead of sand is the pellets. The bacteria just use the pellets as a food source instead of ammonia or nitrite. However they probably use some from the water column. Don't mix the media as most manufactures recommend against this. Make sure that the effluent from the filter is feed into your skimmer to help oxygenate the water. I have an ORP probe on my reactor to monitor its performance. It also helps me keep an eye on if anaerobic conditions develop. The pellets consume lots of the O2 feed to them.

On a side note to Randy Dr Tim's pellets are 100% polyhydroxyalkanoates.

[bertoni]

I agree that a biofilm is a strong possibility. :)