I have had a Caldera Tahian spa for about a year. I change the water about every three months and generally have had very few problems with water balance, etc. thanks in large part to the information I get from this website. The problem I have is cleaning the filter between water changes. I turn off the electricity to the spa and remove the filter for cleaning. But the filter cavity always has dirty water with pine needles, insects, etc. that makes its way into the tub. Is that supposed to happen each time you change the filter?