My skimmer does not seem to be working very good, I am using a net to clear surface debris. I notice the opening is large around 3-4 inches of water entering the skimmer. Shouldn't there be a weir or something to reduce the area of skimming to around 1/2 inch? I think the opening is too large for the skimmer to work. Am I correct or is there something else I can check. If I am correct can I lodge a piece of 2x4 in to narrow the skimming?