I have a California King size bed and sheets to fit it. Well, I have a yucky back and my husband has shoulder problems. Well, we bought a down filled "mattress" to put on the top to make our sleep better (it has). BUT, I can't get the sheets to go over the thing without them popping off. So, I compromise but I don't want my king mattresses ruined since my Dad bought our bed for 1,100 bucks when we got married. Now, I know how to sew by hand and machine. Does anybody out there think that I can solve my problem by sewing enough heavy duty elastic on there to "force" the sheets to stay in place? Or, are there any other suggestions? This is a first in sewing for me and I don't want to ruin the sheets. I have a mattress cover but I like sleeping on crisp sheets. If anybody has an idea, thanks.