[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Fluidized Bed Filters

> > I haven't seen much discussion here about fluidized bed filters.  My
> > local fish store owner thinks this would be a better choice for a CO2
> > injected tank than a trickle filter.  His rational is there would be
> > less CO2 loss due to outgassing.
> I think this is true if the water return was below the surface to
> avoid turbulence. I assume they also generate good water flow?  (They
> need more water flow than normal to keep the bed "fluid", right?)

Actually, the ones I've seen and used all produce very poor water flow
(<100gph).  I have seen the QuickSand brand and I own a Merlin.  They
require quite hefty powerheads to keep them operational but output VERY
little water.  I suspect the additional head of the sand filter really
gives these little powerheads a run for their money.

> However, I see some potential downsides.
> What about mechanical filtering?  Is there a prefilter of some kind?
> Or does the bed do the mechanical filtering?  I've always assumed they
> were best at lots of biofiltering in a small space. 

Generally a sponge prefilter is required or at least recommended.
> What about power failures?  I've heard they good sour quickly when the
> power is lost because they compact quite a bit with no water flow. 

With my Merlin a prolonged power failure (>5min) is generally disasterous
unless I'm around to fix it.  The sand will become very compacted very
quickly and the little powerhead cannot make the sand fluid again without
manual intervention.  What I have to do is open the flow restrictor until
enough flow is generated to kick start the sand into motion and then I have
to re-adjust the flow.  It's a pain in the butt actually.  For this reason
my Merlin is not in use.
> Do you think you need that much biofiltering in a planted tank?

I suspect this much bio-filtration is unnecessary and not the best
filtration option for a planted tank.  They are VERY easy to maintain
I am in the trickle filter camp.  Actually I think a Berlin style sump
would be more appropriate as a large bio-filter is probably not necessary.