Hi~ I hope someone can help me. I have a Hayward DE filter (3 years old) & it seems that a little DE is getting into the pool along with debris that I have vacumned. Last night I vacuumed the water & the pool was free of dirt. My pump came on an hour later & ran for 6 hours. This morning there is dirt back in the middle of the pool. I had the filter checked before hooking it up & was told the "fingers" were fine. What could be wrong??