Re: Protein skimmers (was: box filter)

[plasticolor@guate.net]

>
>Protein skimmers (aka foam fractionators) are not particularly effective in 
>fresh water, primarily because of the size of the airstone bubbles when 
>compared to salt water.  I am cautious to say they won't work at all,
because 
>I had some incidental fractionation with my air-pwered RUGF that left brown 
>skimmate stains on the wall from DOCs that atomized as the bubbles broke in 
>the top of the tubes.
>
>Peter, do you know a way to improve their efficiency in fresh water, either 
>by reducing bubble size, or other means?
>
>Bob Dixon
>
I tried building a few using limewood diffusers, which produce a smaller
bubble than the normal blue airstones.  The stones are hung inside a 2"
polystyrene measuring dispenser glued to the bottom of the skimmer. Their
efficiency depends on skimmer height and diameter, flow rate and the right
relation between air flow and water flow - which I don´t seem to have found
yet. My first two attempts are horrible square contraptions that work great
removing the greasy film on the tanks.  They are fed by a line coming from
a small funnel that hangs underneath a piece of u-shaped styrofoam, to
collect surface water.  Definitely not something you want in a display
tank.  Contraption No. 3 was made from a cilindrical polystyrene spaghetti
jar and it looks a little more like aquarium gear, but is a royal pain to
adjust the flow.  When it works for a few hours in a row, it does expell
brown foam.  Again, to avoid having to adjust the height of the collecting
cup, I used a styrofoam ring with an inverted plastic funnel (actually the
neck of a break fluid bottle, cut diagonally, so the muck oozes out to the
side without having to attach yet another cup on top).  I guess the results
are pseudo-satisfying because when I remove the greasy surface film,
there´s enough organic material + fatty acids to form bubbles that actually
travel through the top.
I´m just finishing building a mold to cast 4" acrylic tubes, 30" long,
which I hope should be easier to work with to try to remove dissolved
organics, rather than only the ones that float on top.  They should work
great in freshwater, but I´m not there yet.

Peter



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