New pool and been running my dolphin cleaner twice a day for nearly a week now. My problem is I have sand in the corners and shelves alll over the pool. Just a small amount. But dolphin not getting it. So twice a day I brush off the tanning ledge, stairs, step ups etc. then I come back 12 hrs later and 90 % of the sand accumulates in same areas? How do I get this up? Do I need some kind of vacuum besides the dolphin ?