Erratic herbie's?

[fkshiu]

Originally Posted by kien

The exact same thing happens with my two Tunze 6105s that I have on a controller. Mine also slow down at night and stop during feeding. I always wondered why that was (the change in volume in the overflow). I guess the powerheads pushing water in the tank force water out of the display tank faster? It isn't an issue for me either though because I do the same thing as you :-)

It seems that the Tunzes create their own wave crest because they push so much water. The crest increases the height of the water in the display which, in turn, alters the amount of water flowing into the overflow.