Tomato trouble

[Flukeball]

Do to my limited sunny gardening space I have gone to some container gardening and have had some very good results.
My trouble is with the tomatoes, the plants grow great, but the fruit has black spots or they are rotten on the blossom end even before they ripen. I use top end soil and water at lease once a day. Sometimes I notice the plants look wilted a little, but when the sun starts to go down the plants come right back on their own.
Can someone please help me with this problem? THANKS!

[Kisal]

Your tomatoes have blossom-end rot. The plants need calcium. There is a Sticky with information here

Your tomatoes may also be suffering from something like black speck, but I would treat for the calcium deficiency first -- the BER -- and see if that doesn't solve all the problems.

It isn't unusual for tomatoes to get a little wilty looking on a hot day. As long as they perk up overnight, I wouldn't be concerned. You want to be careful not to overwater them, as more container-grown plants die from root rot, resulting from too much water, than die from lack of water.