This is vary similar to what I have now and may be able to modify it work like yours. Can you add more detailed pictures and setup info to this thread or PM me which ever you think is best.
White tank on left of picture.
That's the clarifier tank that strains out the suspended solids Very simple. Packed with sections of Wildlife netting with a filter pad or two on top.
A siphon like this pulls in water from the fish tank to the bottom of the filter material while water is being pulled up through the filter material by a small pump that rests on top of the filter material. That water is pushed to the bottom of the biofilter drum by that pump. There is a detachable section the clarifer tank side to be able to reach down and cap it temporarily when doing a water change.
Has a bottom drain in the bottom center of the drum that is simply a 3 inch shower drain that has the grating cut out that is glued into a piece of 3 inch PVC. This is pushed through the Uniseal to create the drain. You do need to cut a washer out of some kind of plastic to keep the drain lip from pushing through the Uniseal.
Here's the shower drain without the grating cut out. Note the white overlap outside of it on Uniseal. This is the washer I cut out of a plastic wall covering to keep the drain from sliding through. The lip on the drain just isn't wide enough.
This photo shows better that the lip is not wide enough:
Length of the PVC from the drain down is not important as long as you have enough clearance under the tank for it to clear the ground once you attach your elbow and another length of PVC. To the end of that is the necessary coupler to glue in a fitting for your hose barb. Then some type of hose is added to to act as your drain. A ball valve is added in line in the hose to release water when you do a water change.
For fingerlings I need smaller openings so I use this riser fitting. Both drains I got at Menards. The riser fitting comes in several sizes.
Here's the pump resting on top of the filter material and the water line going to the bottom of the biofilter tank.
The water than overflows here into the fish tank. That is because the top of the drum is higher than the fish tank. Note the elbows to tangentially direct the water against the tank wall to create centripedal flow (teacup effect).
Keep in mind the system pictured outside is set so high due to the raised garden next to it that gets waste water being already 15 inches off the ground. I wanted to gravity flow the waste water right to the garden by opening a valve.
I'll post some pics with the raft tank installed tomorrow.
Here's a side view of the drain again complete with the diffuser that is mounted on top. This is totally separate of the clarifier drain and tank. I once had them together. Changed it as this allows me to purge solids from the center drain anytime I want but pulling the gate valve.
BTW my furry R2D2 has lost some weight since the photo.
