I think I will stick to the good old water change...
less not be obsessed with filtration and line the pockets of the gizmo
manufacturers. :-)
Roy Hunter
Co-Chairman
ANGFA of North America
visit the ANGFA website at:
http://www.angfa.org
reach me at:
roy at angfa.org
----------
> From: Craig Bingman <cbingman at netcom.com>
> To: rainbowfish at pcug.org.au
> Subject: Re: [RML] Fluidized bed vs. Wet/dry
> Date: Tuesday, May 27, 1997 8:32 PM
>
>
> > Yes that is the system. If you put heaters under it, the purpose of
the
> > whole nine yards would be defeated. This is because water, and the
> > oxygen in it, would circulate through the substrate and arobic
> > conditions would prevale (sp?). But if all you wanted was and under
> > gravel heatering sys then I cann't see why it would not work. BTW the
> > nylon cross stitch/craft "fabric" works better than widow screening
> > (IMHO) because it stays put once a little wieght is put on it, its also
> > easier to size.
>
> I wasn't arguing for or against heaters, but there is some
> misunderstanding about how plena work. Diffusion is not fast enough to
> give much denitrification in the sand or gravel bed. Some form of mass
> flow must happen. Plena seem to speed that up, although in a reef tank,
> which typically has much higher water motion than a freshwater tank,
> there is enough pressure differential over just plain sand beds (with no
> plena) to drive mass transport.
>
> > > It isn't that porous, and I think the denitification potential of
live
> > > rock is usually overestimated. It is variable. It also might be
> > > difficult to find appropriately porous rocks for a freshwater tank
that
> > > were not made of calcium carbonate.
> > >
> > > That does work. Which is why I suggested a deep bed of coarsish
gravel
> > > for fishtanks. The gravel in our freshwater tank always has gas
bubbles
> > > in it, which I presume are mainly nitrogen.
>
> > I'm not sure how to respond about poracity of live rock, the rock I
> > have is very porous but some of it was not "live" when I put it in, it
>
> Depends on what you mean by very porous, I guess. As I indicated, this
> is quite variable in what is sold as live rock for reef tanks, and aside
> from tufa rock, which is calcium carbonate-based, I don't know of any
> rock that one might find that is very porous. Pumice I suppose, but lava
> typically is high in sulfides and metals, and I'd not want that in my
> tank, and it might be a bitch to get it to sink. ;-)
>
> > carb. You may well have a good point about the nitrite though, I had
> > not really considered it. I'll have to look into it before if I ever
> > get around to seting up another "experiment" ;)
>
> Just something to watch for if you try this.
>
> BTW, people have used plena driven with very slow pumps in freshwater
> systems. They denitrify like crazy, and yes, there is nitrite in the
> output, so if you are forcing the flow, you can just divert that over a
> trickle filter and take care of that.
>
> I don't know how they will work out uncontrolled in a freshwater tank.
>
> Craig