Physics for a Refugium: Help Needed

[Blue H2O]

I set up a 5g refugium for my 20g tank. The fuge isn't drilled, and I don't have an overflow box.

For right now I have the fuge linked to the main tank by 2 reverse flowing syphon tubes. When I do water top offs in the main tank, the water level in the fuge rises to the same level. This shows that the tubes are passing water.

My question is are the tubes actively moving water constantly, or only when the level changes in one tank? I don't know if the tubes are still acting as they did when I first started their flow. In other words are the tubes still acting as reverse flowing syphons, or are they just stagnant until I do water changes?

This is confusing to me, but maybe clear to some of you, thanks for any help.

[fishfreek]

Water will always try to find its own level. If you have the fuge below the main tanks water level water will flow into the fuge until the water level in both tanks is the same. If the water level in the fuge is higher than the wtaer level in the main tank the water level in the fuge will drop till its level with the main tank. Once the water level is the same in both tanks water flow in the tubes will stop until the water level changes in one of the two tanks and then water will flow out of the high tank and into the low tank.

[oyf709]

not sure if i am off topic or not but u can try keep ur refugium above the main tank, drill a hole on refugium and use a syphon tubes draw the water down to the main tank(refugium can be use simply just a bucket since you won't really put any live stock in it. and simply just use a slow power head to shot the water back to the fuge. Flow doesn't need to be fast.