Just opened our small koi pond for the season (vacuumed and turned on pump). Mesh pad in place and it's clean. Haven't added any carbon, filter media or chemicals yet. The floating weir inside the skimmer basket is sitting too high and therefore is not pulling in debris. Pond water level is fine. Connection between pump and waterfall is with underground tubing. But something isn't pulling water rapidly enough to make the skimmer work well. Ideas or suggestions?