I have a 150lb sand filter. I purchased 3ea 50lb pool filter sand bags from home cheapo (hence 150lbs). I put all three bags in, however the filter is 3/4 full. Does the sand need to be close to the top of the pvc pipe in the filter? Say a few inches from the top? Also, I turned it on for the first time and for roughly a minute sand came out untill it cleared. Is this normal, or is my pump too strong for that size filter?