30 minutes for flood and drain

[tom]

Hi,
I am building a 6 plant flood and drain unit with 2 liter coke bottles....My question is how do I time
the flood and drain.....and how often? I have a 24hr/30min on/off timer but is 30 min. too long to
flood the unit? This is my first time building a unit it will be used for Tomatoes and Cucumbers.
Any help would be great! Thanks,
Tommy Agoitia E-mail (agoitia@stic.net)