I started up my pool yesterday and last year when winterizing I took plug off the sand filter and about 2 - 5 gallon buckets worth of sand came out ... The owners manuel said that this should not of happened , but it did ... We went to our local pool store to get some sand and they told me that the reason sand came out of the drain hole was because of it having a broken or cracked lateral . so we emptied the filter and I inspected the laterals and the whole unit ... No cracks or visable problem so I put it back together and added the recommended amount of sand , which for my filter was 300 pounds ... We started it up and about 2 hours later I noticed sand at the step jet so I stopped the filter and put my hand down into the pool and pulled some of it up and it was the sand ... So I took it all apart and emptied the sand out to get the unit out again to see if I missed something , but again no noticeable damage ... I was moving the laterals up and down and one easily came out though but am not sure if I caused this or it was already damaged and need replaced ... Help !!! Also my water really stinks and is greenish brown and can't see the bottom ... Tests show 0 chlorine , but yesterday when I got the system going and thought there were no problems I had already shocked it and added clarifier and algecide , but this morning still 0 chlorine ... Also is it hard to get the sand out of the bottom after I get the filter fixed ??? I am very disappointed also in a decision I made last year getting a mesh cover ... It seems very dirty and someone else who has a mesh cover told me the same that during the winter season all the dirt filters down ... I am thinking this winter of putting the mesh cover on and then rigging up the tarp the previous owner had until march and then removing the tarp to allow rain water to fill pool up to skimmer ...