Thats the way I would do it. Bottom tank drain to the bottom of the clarifier with a ball valve. I would also put in a tee at the bottom of the tank with a drain hose attached. I have 2" pvc shower drains. I like these because you can easily take the plumbing apart without having to install unions. They were only about 6 bucks at Menards. They fit through a 3-1/8" diameter hole and come with gaskets.
Only problem is the existing hole in the stock tank bottom is 4 inches in diameter. Maybe I can still find a large drain that will fit?
On the outflow of your biofilter, you could plumb some pvc to create your circular current. You may have to diffuse the flow of water back to your tank to get the right current speed.
If you need more solids filtration then you could side stream with another pump. I would rather put in another barrel with a bag filter for that. Up flow out of your clarifier and down flow into the bag filter. You then put the pump in this barrel. You could still also side stream if you really need it.
You could then run an inline uv system directly out of the pump. With the polished water, you will have fewer cleanings of the uv unit, and it will work better.
What specific goals would you want to achieve with UV? The pond units you see are generally for destroying algae, and may not destroy viruses etc...
I was thinking if I did go with UV of using a bulb powerful enough to kill bacteria, etc. I have a UV system minus the bulb for ponds that was given to me...?
Thanks for the info JKB!
