If you're growing indoors, you'll need to hand pollinate. I believe peppers are self pollinating like tomatoes. you can simply shake the plant a bit once or twice a day to get some pollination.
I use an electric toothbrush and "tickle" the backs of the flowers with it. Last year I had 100% fruit set doing that.

I had a similar problem. Turned out that I had too high of EC. Take it down to about 1.0 (with 0 EC water) and eliminate nitrogen almost entirely. Some will tell you that heat causes blossom drop. Interesting that they grow best in the tropics if heat bothers them, eh? I also passed this error along because I read it so often on various sites by "experts" without considering the obvious fact that tropical plants don't survive in tropical heat without being able to fruit. In fact, I think that is a very common claim despite the logic. I read all the time that peppers won't set fruit if temps reach over 90. It's a wonder how the most productive areas are those that are more often over 90 degrees than not. It's also a wonder that I produced so much last year (ground garden) when our temps were over 90 most the summer. Anyway, I digress. . .

I first followed the heat advice with no luck. Once logic set in, I figured it must be something else. I found that greatly reducing EC and specifically reducing the nitrogen, the peppers started growing like crazy. I just harvested nearly 70 peppers over the last 2 weeks from one plant. I have a few left to harvest yet, but am waiting for them to ripen just a little more. If I would have realized the problem sooner, I suspect that my plant would have been more productive. Also, I pruned it a lot due to running out of head space.

Good info Joe Jr.

I'd have just figured it was a pollination problem but there's a lot more going on than just that it seems.

Flower drop probable causes for chiles:

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.

I did some reading up on this and there's also some concern about balancing the vegetative growth with flower development.

If your plant is trying too hard to make flowers and isn't growing enough foliage to support everything it can end up having to abort the flowers because there just isn't enough support structure for everything metabolically.

Gary, where did you read that?

I don't remember exactly where I read it, but I memorized the picture they had. Pepper plants like to fork and then grow a flower at each fork. Supposedly to maximize your yield and keep a constant harvest you're supposed to cut off the first flower and both of the flowers at the second fork.

Then you let the ones at the third fork grow and cut off the ones at the fourth fork.

After that, let everything grow.

I couldn't tell you first-hand how well it works, but that's what I read.

I have had similar issues with most of my Hydroponic Peppers, even the Bell's.

I found that I do not need the Grow formula, I need the Bloom from birth to cradle for my Peppers because the Bloom has too much Nitrogen. There simply is not a "Pepper Formula" out there and almost every plant likes Nitrogen. I am now using the Botanicare brand of Hydro Solution. It has a 2.5 - 2 - 5 formula. The particular one I use is called Pure Blend Pro Bloom (for hydro gardens). It works fantastic on Peppers.

High temperatures do cause the blossoms to turn yellow and fall off if the temp stays above 90 degrees. As pointed out by another forum member, air flow is huge. And hand pollination is superior to even bumble bees believe it or not. I use an artist paint brush (something found in a water color artist kit) to pollinate the flowers by hand. This needs to be done early in the flowering stage until the powdery white pollen ends up all over the end of the paint brush. Often times you can visibly see the cloud of white powder come off the flower when you hit it a peak time. If you can do this to each flower, you will get a 100% or very close pollination rate.

Lastly for some reason during the heavy flowering stage the plant needs more calcium and more magnesium than it can from the nutrient formula. I add about 10 drops per gallon of Botanicare Cal-Mag Plus through the heavier flowering periods.

I have gone from getting one pepper per 10 flowers to not loosing more than one per 20 now on my pepper plants. I do not think it is just one thing, I think its the combination of things.

Also I started out using 1500 ppm or 2.1 EC and found out that my leaves were curling, especially when the plant forked and wanted to create a bunch of new leaves and flower. I then found out over time, that .50 EC is perfect for hot pepper plants all through their life except when seedlings where I use a .35 EC.

I am not saying this is the only way to grow peppers, but it has helped me a ton. I now have: Serrano, Anaheim, Goats Weed, Naja, Jalapeño, Thai, Thai Dragon, Medusa, Hungarian Carrot, Yellow Hot Wax, Cayenne, Bell, Super Chile, Chile Super Chile, Tabasco, Pepperoncini, and Habanero all growing at the same time in my grow room!

If you are curious as to what I have done and want to see some pictures, visit the link below

Here is a link that might be useful: My Hydroponic Garden

I'm glad I saw this - I had just started having the exact same problem with my sweet pepper plant (unknown type). Sure enough, I was feeding it Grow nutes.

Popped down to the Nursery and picked up some bloom booster nutes a few days ago, so keep your fingers crossed for me!

I finally gave up on my pepper plant. It was growing in a vermiculite/perlite mix and I was giving it a low N bloom mixture but for some reason it just wouldn't bear fruit for me.

So I pulled it up, shook the roots as clean as I could, and planted it in a soil pot outside. Maybe I'll get lucky. I'll retry peppers later on when I get a better hydroponic system (I'm thinking ebb & flow).

I noticed you said that you popped down to the nursery to pick up bloom-booster nutes, hydroponica. Do you mean regular fertilizer for gardens or hydro nutes? A bloom booster for the garden is still going to have too much available nitrogen, I would think. And usually not enough micronutrients. Both can stress the plant.

Oh and for those of you that still hold on to that claim that high day temps cause blossom drop, explain why my outdoor plants are still producing strong when we had the hottest week of the year this past week. I have two young plants in pots (using a tomato fertilizer for gardens that claims to contain micros) that set huge fruits just this 90 plus degree weekend. Not one single blossom drop on them. But, I did experience a few blossom drops on my indoor plants which are in a nice climate controlled environment. Maybe because climate isn't the only difference. The other differences are nutes and obviously the lighting. Theories aren't really theories when challenged and they fail. Peppers thrive in heat. Tested. Proven. Again. Obviously extreme heat in dry conditions is going to increase stress on any plant by increasing transpiration and dehydration. But, most people on here aren't growing in 95 degree plus heat for a long enough period of time to cause such stress and in hydroponics the constant supply of water should off set the rapid transpiration a bit. Especially if you mist the leaves at all.

The stuff I got was a full set of nutrients, macro and micro, but like you said I think there was still too much nitrogen.

I put it in a pot outside and it went through some typical transplant shock but has already started bouncing back and even set some fruit.

With luck I'll have some decent peppers before it gets too cold. Of course I could always just bring that pot inside and finish off with my lights. Yeah, that sounds like a plan.