Pollinating Hydroponic Tomatoes: Wind May Not Be Enough

My hydroponic tomatoes were dropping blossoms. Lack of pollination is one possible cause. Most of what I read online said tomatoes self-pollinate quite easily. Wind pollinates them naturally outdoors. I had setup a fan to blow on them briskly every 10 minutes. I figured that was plenty.

I did a test using a sonic toothbrush to vibrate the blossoms on one half of my plants. (In nature, the vibration of insects wings releases the pollen.) A few days later, those plants started setting fruit, while blossoms continued to drop from the other plants. So it appears in my case at least, wind was not enough.

The bud on the left didn't get pollinated. The bud on the right did. That's what we're looking for!
The bud on the left didn’t get pollinated. The bud on the right did. That’s what we’re looking for!

I had two very different varieties of tomatoes growing, both had the same symptom and both responded the same way to the manual pollination.

My conclusion, self-pollination is not assured, and even wind may not be enough.