I feel that my water level is a little too high. I read in here that the idea over should be halfway up the skimmer box and or tile. Mine is towards the top of both. When I try to adjust the filler by pushing the plastic box down it stops filling with water and therefore gets the water level to be lower on average. However I am not able to keep the little box down. It comes right back up. How to you permanently lower it to keep the water level lower?