Safety Covers must always stretch tightly across the swimming pool. After the initial installation, some stretching may occur. The springs on the safety cover should be compressed 50%, you may need to readjust the straps. The water level in your pool can not go below 18” from the top, as a safety cover is designed to set down on the water with the weight of snow and ice. Without having the proper water level, the safety cover will stretch too far, placing undue strain on the cover and voiding the warranty.