Sometimes when cucumbers begin blooming. they will set all female or all male blossoms. The exception is some of the new varieties that set all female and do not need pollinating. Most varieties need pollination.
The male blossoms are on the end of a small stem while the female blossoms are on the end of a small cucumber. After a period of time, the plant will set both types. It would do no good to hand pollinate until both types are present.

Some varieties of cukes need a pollenator. Sometimes the pollenator seeds are of a different color in the same seed pack...

For a great self-pollinating cuke try Tyria from Johnnys. Yes, at $1 a seed it's pricey but the long European cukes are sweet, delicious, seedless and do not need peeling. Each plant will produce as many as 40 cukes. Well worth the money.

Hydrotaig...

You're problem probably doesn't have to do with pollination, at least from my experience. Most cucumber varieties today are self-pollinating hybrids, so unless you're working with an heirloom variety...

Cucumbers will generally produce many more flowers than they can support as fruit, especially under artificial light (even HID). The secret to successful indoor cucumber production is to thin out the flowers after they develop, leaving one flower (or fruiting site) every 18 inches or so along the vine, leaving no more than 4-6 fruiting sites per vine.

Try thinning out the flowers and I think you'll see tasty cucumbers in your future. Proper trellising helps as well, keep those leaves bathed in light.

Hope this helps. Good luck!

Jeff Edwards
Harvestmaster