What media are you using in your biofilter?
MB3 sold by this company:
http://www.w-m-t.com/Products/WaterTek_MB3_Moving_Bed_Media.phpIt's 1/2 the price of Kaldnes, works better, and is made here in the U.S. vs. Kaldnes that is now made in China. Only $25.00 per cubic foot and one cubic foot is 184 square feet of surface area. I really like the self cleaning aspect of moving bed filters.
And is your pump on top in your clarifier pulling the water out and then the siphon puts it back in?
Yes. When water is pulled out of the clarifer tank the siphon compensates via gravity and pulls water out of the fish tank. The siphon always tries to keep the water level the same between the fish tank and the clarifer tank. Hence why water comes in via the siphon as water is pulled out of the clarifer tank.
Have you ever had an issue with one of these getting clogged up or other issue to cause water to come run out of tank?
No. If your fish are small enough to fit into the siphon you make a screen to keep them out. (although you want to periodically clean the screen if you are feeding heavily as in fingerlings.) I do that by having two screens. The fish are scooted away from the screen, it's removed and immediately the new clean one is placed on. Then the one removed is cleaned and used for next time.
Only problem I have had is not completely filling the siphon before it's initial use and having air slow it down. But it won't overflow if that happens. It would be just the opposite. That is more water is pumped out than is coming into the clarifer tank and the water level in the clarifer tanks gets low.
If you fill the siphon and keep both ends under water you will never have to fill it again. You simply drop the siphon in the fish tank, allow water to fill it up and cap the end you will be pulling above water to place into the clarifier tank. As long as both ends stay under water you will never have any issues.
What size pump do you have in the clarifier?
It's mag drive 60 watt pump that does about 14 gpm I think. I've used as small as a 30 watt and 10 gpm and it worked fine. The mag drive pumps are very efficient and last a long time.
Do you also have a drain on the bottom of your fish tank as well?
Yes the one pictured in an earlier post is the center drain system for the tank. The clarifier tank has it's own simpler drain. See below for fish tank drain system:
