Need Help Por Favor!

First of all, let me introduce you to my setup. I have a rectangular planter box filled with Perlite to create a hydroponic setup. I have a flourescent worklight with two 40W bulbs, a exhaust fan to get rid of the heat, a fan that constantly cirulates the air, and a constant tempature of 79 degrees Farenheit.

The problem is....
I was watering my plants twice a day and they were growing nice and strong and yesterday, my friend informed me that i should water it once every other day. So i had watered it yesterday morning so i didnt water last night. Today when i check my plants all but two are leaned ver wilted. The leaves seem to be fine. So far i have made a small mountain of perlite around the base of the plant to add support to hold up the plant. Any ideas what went wrong? What should I do to ensure this wont happen again? Could it be the watering? How often should i water?

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i think that you plant needs to be watered because the pic shows a plant that is streching, the roots are growing right now and are searching for water, while, on the other end the leaves need light....about the watering schedule i think that if the medium drains too fast and does not hold any nutrients then you need to water often, propably you need to turn to your 2 waterings every day......
hydroponics is a grow in which you have to provide somehow a constant flow of nutrients so as the plant feeds constantly, the roots do not have to stress looking for food etc.....your friend would be right if the grow would take place into soil with some perlite mixed into it for better draining......
i am not an expert on this but i think i'm right.....

For the update: The plants are doing well. Today i sealed off the original drain holes and left only two, on opposite sides of the box so that it retains its water more conservatively. Hopefully this should resolve the problem.
also, do i need more light?