I have to agree with blossom end rot. Do NOT water them every day. That is way to much water for a pepper plant. Also add some calcium to your soil. IE: crushed egg shells will do nicely here, and is a cheap solution.
Pepper blossom end rot is caused simply by a calcium deficiency in the pepper plant. Calcium is needed by the plant to help form the cell walls of the pepper fruit. If the plant is lacking calcium or if the pepper fruit grow too fast for the plant to supply enough calcium, the bottom of the pepper begins to rot, because the cell walls are literally collapsing.
The calcium deficiency in the plant that causes pepper blossom end rot is commonly caused by one of the following:
A lack of calcium in the soil
Periods of drought followed by large amounts of water
In the long term, adding eggshells, small amounts of lime, gypsum or bone meal to the soil will help improve the levels of calcium and will help you avoid pepper blossom end rot in the future.
It sounds like blossom end rot. The rot is caused by calcium deficiency in the plant. Over-watering, too much nitrogen or low calcium in the soil can be to blame. I have read adding lime to the soil can help, though I'm not sure when or how much.
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