I found a good deal on a 1.5 hp pool pump. Since my Intex pump was getting noisier,I bought it and installed today. Wow! does it ever push water! I hooked up my vacuum hose and turned the pump on. The pump started surging right away. What would cause this? I backwashed and retried with the same results. Any Thoughts?? I have an Intex 16X48", new 1.5 hp pump, Intex sand filter, Intex SWCG.