There are a couple of things I've noticed growing sweet peppers. One is that too much nitrogen will cause blossom drop. Two is that so will inadequate lighting. I did a little experiment not long ago with tomatoes and peppers and it turns out that the peppers outside under the sun and in the heat had no problem fruiting at all. The ones inside under T5 lights and a much more climate controlled environment didn't hold blossoms for a long time. All seeds from the same packet. The environment wasn't completely enclosed and had a fan, so CO2 shouldn't have been an issue. I don't know how well CFL's really light things up. Ever check with a light meter?

Interesting. I know my son-in-law had a hell of a time with his indoor peppers and as soon as he put them outside he had a huge amount of fruit forming.

He uses CFL lights as well.

It makes sense if you think about it - a plant won't waste energy growing a fruit if it doesn't have enough energy to finish the job, and plants get their energy from the light.

He thought it was nutritional issues (it may well have been a factor) but the extra light might well have been the difference.

Flower drop probable causes:

1. Day temp too high >95F
2. Night temp too low 3. Too much nitrogen fertilizer
4. Too much water
5. Low light levels (reduces fertility).
6. Very low humidity (reduces fertility)
7. Poor air circulation (air circulation contributes to pollination).
8. Lack of pollinating insects.
9. Size of pot

10. Too much mineral in feedwater.