Water returns, Powerhead CO2 injection

First off, big thanks to George for mentioning positioning of water 
returns a few weeks ago.  I have a 55 (actually 45) with an overflow 
skimmer, and since it's been set up (just turned 2) I've had the return 
going to about mid-tank (not wishing to scare off the bottom feeders).  I 
always have some mulm build-up here and there (just minor amounts).  The 
return is a 3/8" vinyl tube run into some 1/2" PVC that loops over (hangs 
on) the top of the tank.  There is a little hole on the upper EL part
just above water level that acts as an anti-siphon should the power drop 
(very important!).  Every joint is glued except for the 1/2" PVC between 
the two ELs inside the tank.

     |    __|__    O
     | EL |   | EL |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     |    |   |    |
     ====== T ======          
     |    | A |    |       >-D
     |    | N |1/2"|
     |    | K |PVC |      
     ======   |    |
      |  |  W |    |
      |  |  A |    |
     /  /   L ======
  vinyl     L |    |
  tube        | EL |
  from pump   |    -----|  out
              \_________|  to tank
With this sort of arrangement, I can adjust height of the return by 
subsituting different lengths of 1/2" PVC tube.  Practical upshot: I put 
in a new tube a week ago that returns the water just above the gravel, 
and now the gravel is sparkly clean.  Even the mulm that settled all over 
the plants during the cleaning vanished (usually I have to go in and 
shake it off or let the fish clean it).  The only bummer will be that the 
baby Kribs probably will have less stuff in which to root around for food 
when I'm not injecting brine shrimp.

Re: CO2 injection through powerheads

I originally used a bubble counter, but quickly discovered that if you 
put a 3/4" piece of clear rigid tubing under your powerhead, drill a hole in 
the tube about 1-2" below the powerhead, then poke the CO2 line into 
there, then you can count the bubbles as they emerge.  Impale the rigid 
tube into a sponge and you have a powerhead-driven sponge filter/CO2 
injector.  You can also buy a corner box filter for a few bucks, which 
comes complete with everything you need except for the little hole 
halfway up the return tube.  This also solves the problem of where to 
hold the powerhead.

  - Erik

Erik D. Olson					              I'm baaaack!
eriko at wrq_com (was olson at phys_washington.edu)