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Re: NFC: A filter idea

	btw, Martin, cross-posting to both nfc and nanfa does not send the
message to nanfa at all. This is to avoid bounces from people who are not
on both lists. 

	In ref to the Archimedes screw ... You could get the screw part of
plastic in some childrens' toy sets. Look for the "construction" sets or
sets with moving trains or other gadgets. A large plastic piece in the
shape of a corkscrew should be available somewhere. The problem would be
finding a motor to drive it. Also, how would you hook up the motor (drive
belt, motor drives the screw directly like a drillbit, etc.)? You could
make your own screw if you can find a stiff plastic piece with a 'x' cross
section and heating and twisting it carefully. 

	Hmm, I can already picture it ... inclined stiff plastic tube,
plastic core with a teflon ball/socket joint at the bottom, two inches off
the bottom are holes in the outer tube for water intake, the core has a
corkscrew shape from the intake all the way to the top which is open. The
motor drives the core (heck, it could be a modified powerhead which drives
the core). The water rises up the inclined tube, pours off the top. 

	but, because of the open ends you don't get the added benefit of
vaccum helping raise the water and maintain water level. Also, I am
guessing it would be quite inefficient way to move water ... a lot of the
power would be dissipated as heat due to the increased area in contact
with the water (friction).

	btw, what do you mean "beneficial" *plankton*?  


On Sat, 8 Jan 2000, D. Martin Moore wrote:

> I have always wanted to replace the standard impellor in an outside 
> power filter with an archimedes screw.  I claim it would be much 
> more efficient, with the side benefit of not being destructive to 
> beneficial plankton.  Any thoughts on this?  Does anybody know 
> how to fabricate such a part?
> Prost,
> Martin
> ------
> "Cry to it, nuncle. as the cockney did to the eels when she put 'em i' the
> paste alive; she knapped 'em o' the coxcombs with a stick, and cried 'Down
> wantons, down!'"

Sajjad Lateef       <http://www.lateef.org/sajjad/>
sajjad at acm_org      sajjad at lateef_org

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