I have a Jacuzzi "Laser" filter which I've emptied sand and am refilling. I filled the tank up halfway with water and began putting in one of four 50 lb bags as the recommended weight for my 19L model is 200 lbs. I've finished the third bag and honestly I'm not sure how I'm going to be able put the valve assembly back on if I add the fourth bag. Are there any absolute requirements for filling these things or does the sand "settle" after awhile?