Re: Under ground filter or not?

[IDMiamiBob@aol.com]

<< Bob Dixon, could you give a more detailed description of your DIY
< air-driven reverse UGF... I am interested in how this works, since I've
< only ever encountered powerhead-driven RUGFs >>

Okay it's like this:
I built it for a thirty gallon tank.  I started with a drop ceiling "egg
crate" from the home center.  I glued marbles on the bottom for legs.  I
covered it with "plastic canvas" from a craft store to keep the gravel from
falling through.  In each of the two back corners I cut a one inch circle.
 Into this I glued a length of 1" aquarium filter stiff tubing from the LFS.
 
    NOTE: I precut all tube lengths before gluing
At the top of this tube I installed a 3/4" PVC street elbow from the home
center.  these street elbows are not carried by everyone.  I finally found
them at the Depot.  The large end of 3/4 inch elbows and tees are slightly
larger than the 1 inch tubing, and will hold on fine with silicone.
To the other side of the elbow I installed a vertical 3/4" tee.  I installed
a 1 inch tube to the bottom of the tee, down to the bottom of the tank.  Then
another street elbow, and to the street elbow, a regular elbow pointing back
up.  I installed one more tube back up toward the surface and capped it one
of those guards that come with power filters to protect against sucking up
fish.  I originally used a fan shaped guard, but found that the straight ones
would allow me to better skim the protein and fatty acid slime off the
surface down to the filter, where something seems to be digesting it.
Stick an airline down through the tee and into the middle tube, all the way
down.  Stick an airstone on the end of it if you are so inclined, I get the
flow rate I want without it.
You can build it cheaper by using 3/4 inch PVC, but you can measure flow rate
when you can see through the tubes, and they are a bit less visible.
 Meeasure the flow rate by dropping a single drop of Methylene blue or even
food coloring onto the surface next to the intake.  If you know the length of
the tube, and it's diameter, a little algebra and the time it takes for the
dye to travel the length of one tube, and you can figure it out.
If you get water up through the top of the tee before you achieve the flow
rate desired, add some PVC tubing.  I am getting 35 gph on each side without
it.  I have one and a half to three and a half inches of gravel for a
substrate, more than enough for adequate bacterial filtration.
Just as a side note, I also use sponges for some of my tanks, and have since
they first came out.  Yes, they are great, and I agree with everything that
has been said for them.  But my A. cacatuoides are spawning in the 30 gallon
community tank, and the female is tending fry.
Bob
PS- the deencapsulated shrimp eggs I got from Kaycy and Darren are great.
 Just measure them out and drop them in the tank.  The fish suck them down
and the froy are doing good on them.  No muss, no fuss, no bother.