Re: Eheim diffusers

["S. Hieber" <shieber at yahoo_com>]

J & D Olberding said:

> Don't necessarily rule out use of Eheim diffuser
> IMO, they do a good job of diffusing, particularly on large tanks. 
> Remove
> the check valve that comes with it, install a regular check valve and
> a good
> quality needle valve. That will let you  easily adjust and control
> the rate
> and should have  no problems with excessive flow. I have been using
> Eheim
> diffusers with this method for months on some 20+ tanks with no
> failures or
> problems.
> re glass disk coming out. If unit is correctly put together is no
> chance of
> that unless perhaps one smashed the glass disk.

The disk sits inside a rubber ring which servs as a gasket.  The disk
fits snugly inside the gasket and is thinner than the gasket.  The
opening of the top piece of the diffuser, which sits on top of the
disk/gasket assembly, and the bottom piece, which rests underneath, are
both slightly smaller in diameter than the disk.  Thus, the disk cannot
pop out of the unit entirely.   If the upper and lower pieces are
twisted together tightly, the disk cannot rise or fall by more than the
difference in thickness between the disk and the washer, wich is
somewhat flattened when the top and bottom pieces are twiested
together.  Twisted together too tightly and you can break the disk. 
Twist together too loosely and the disk can be moved out of place if
bumped or pushed by a lot of pressure, say CO2 in compressed gas form. 
But regardless of how it well it is twisted together, it does seem that
you can get leaks (of large rather than small bubbles) where the disk
meets the gasket.  This seems all the more likely, given that one must
often disassemble the unit to properly clean it.

Does it leak often?  Apparently not.  Is it worth the risk?  Depends on
what is at risk, how much your fish are worth.

Scott H.

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