i don't have a top off (i wish i did) but if you neglect the water level and don't take care of the evaporation.....yes, it would run dry. one way you could solve that would be to drill a hole on the left side of the pre-skimmer or don't use one of the tightening screws (which would leave a hole) which would allow water to enter and stay at the same level as the rest of the tank (exactly the same way the right side works with the sponge at the bottom). you can check out a pic of my set-up under my pictures and/or profile....if you like, i can take a close up picture of the skimmer although i don't think it would give you a better idea. i basically top off about 1/2 gallon per day to resolve my evap issues...hth. _________  |