overflow experiences...?

[BCOrchidGuy]

I found the U tube type grew alot of algae in them, coraline algae as well. You'll end up with bubbles all the time at the top of the U which will slow down your water significantly so like Danny said, put an airline in the top and run that to a power head (like where the bubble tube add on would go. That will draw water/air out of the U tube and keep your tube from developing bubbles.

Doug