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Re: NFC: A filter idea

>  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.

Hmm, I'll keep my eyes open.

 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. 

What I have in mind is a retrofit for an existing OPF.  
>  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).

All I have in mind is replacing the existing impellor.  This is similar to 
the idea behind the non-cavitating propellor used by some ships.  By 
reducing cavitation you increase efficiency (and decrease noise).  
Compare the shape of the screw to they typical impellor used in 
today's OPF's - I think they must generate a LOT of friction.  

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

Anything small enough for fry to eat.


"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!'"

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