this skimmer has flow rates on the output which in turn causes the water level to rise in cone and after 1 year of use the only way to get foam now is to turn the valves and have the water about a quater up the cone,the instructions dont mention anything about these valves anyone know the correct set up of this skimmer (all pump parts clean) also pumps suction doesnt sound as strong as it did (air hole clean) thanks for any info