Just opened our inground pool (closed it ourselves last year and rented a powerful air compressor to force the water out of the underground lines) and our skimmer does NOTHING. Everything else seems to work fine... the main bottom drain is pulling water and the water is going fine out of the 3 water returns. The fountain also works fine. When I close the main drain to test there is no water being pulled in (from) the skimmer. I can't tell if the maybe the valve to open the skimmer line is defective (not actually opening) or if the problem is more sinister. Can you tell me what I should check before calling a technician?