Fluidized Bed: vented with glass beads

This fluidized bed filter is on a 300 gallon cube tank with 2 large redtail and a Gar so there are tons of solids (ugly goldfish and tilapia fillet) but they pass through sand and settle in the sump. The sand is purely a site for thin film Biofiltration which is the most efficient form. If you let the solids build up in the biomedia heterotrophs out compete the autotrophs and the efficiency drops.
If the sump is still the solids just settle out out. It's much easier to vac out a sump than to clean something like a pad that trapped the sticky carbonaceous solids(mulm/detritus). I vented the stack and it got rid of the bubbles. This picture is with the sharp sand without bubbles. The venting and removal of bubbles will allow the use glass beads which fluidized better than the sharp sand and have a higher surface area.
Glass Beads, perfectly smooth and round.

What do you Dream about?

Gravity Fed Fluidized Bed

I made this fluidized bed filter out of some polycarbonate scraps. It has large grain sandblasting sand so the bubbles from the gravity fed water doesn't eject the sand into the sump. Holds about two gallons of sand. It is not fully fluidizing at this point but all the sand is moving. The holes are left over from the sides being aquarium lids. Most of the water flows out the sides that form the angled sides. I'm working out the kinks of an air purge system to so I can put finer media with more surface area.

Direct Video Link.

A Few Good Books For System Fauna ID

Tank Plumbing

In my fishroom all tanks have at least one bulkhead. Lager tanks have two out the back. The holes a 1 3/4 inches for a one inch bulkhead. The hole is drilled 6 inches in from each end and 4 inches down from the top.
One bulkhead is plumbed to drain so it can be used to empty the tank by rotating the pipe down or as the primary drain if run on a flow through configuration. To make this work as a drain that can siphon the tank empty the plumbing needs to be vent free to below the tank. Just think of it as a siphon tube running through the wall of the tank. If you vent at the bulkhead you can run the intake on the bottom without emptying the tank. Generally I plumb the first way and if I want bottom suction I simply put a tee at the inside of the bulkhead instead of an elbow.
The other bulkhead is plumbed to a central filtration system in a surface skimming configuration. Water is supplied to the tanks via a plumbing manifold with a supply valve at each tank. Water can be from the recirculating system or through a hose for large water exchanges. All tanks have box or sponge filters.

Ranchu mold mark on a Gatorade lid

Soon after the Ranchu bug bit me I found this on a Gatorade bottle. I
thought I was crazy seeing Ranchu every where. Just found it in my
desk and thought I'd post a picture.