Since we are still on this topic, I will share the incident that nearly killed my family's enjoyment of the hot tub last Spring. We hadn't used it in a few weeks and my wife got in one night and was relaxing in the dark. Then she noticed some black stuff floating, then she noticed black stuff all over the bottom...at which point she realized that she was soaking in bee soup and I heard loud screams and came running. There were thousands of bees in there...floating, on the bottom, everywhere...I had to drain the thing, change all the filters, etc., but everyone is real cautious about using it now. My cover had a gap they could get through, so I got a new cover and haven't had a problem since.