Quote Originally Posted by Prodaytrader
if you want to water in increments less then 15minutes then you will need something like this : ebay timer if you can water in increments over 15minutes then any timer will work. Most use a weekly timer from home depot. It needs to have daily features so you can schedule watering times on a weekly basis. The issue your going to have is watering for less then 15minutes several times daily. Lot's of people use systems that have them water for 10, then dry for 30 or something along those lines. That happens 10 or 20 times a day which a weekly timer cant handle. Most timers will kick on water for 15 minutes then turn off. A weekly digital timer with multiple on/off's per day will allow you turn the water on at 10:00 then turn it off at say 10:03 but that's about it for that day. You might could schedule one further event that day but most timers aren't built for multiple daily functions. Either the timer is built for repeating functions with no weekly scheduling or it has a schedule feature with no repeating options for intraday watering.

I actually use two different timers but now that I am writing all this out for the life of me I dont know why. I have one that turns on all power (fans, lights, water pump) and then that kicks on the watering timer which floods for about 2 minutes once per day. In retrospect I suppose I could have used a weekly timer since I only water once daily but I had it lieing around from a previous grow. My next grow will have me water every 3 days for about 3-5 minutes so I will probably just use a weekly timer there. Set it to turn on every 3 days, then turn it back off 3 minutes later with another scheduled event. Should be just fine for my needs.
thanks for the advise, I am asking for areoponics system and what brands to choose from. It sounds like this advise is for groing in soil.