I should imagine it would depend on what you're growing. I run my cloners 24/7, but I leave plants in there no longer than about 2 weeks for the most part.

A lot depends on your relative humidity. I've never been to Thailand (if that's where you are really), but my hunch is the humidity is high and my best guess would be to do a trial and error experiment using different time intervals.

Your plants will benefit the most by having their roots exposed to air in between nutrient-sprinkling sessions. Just be sure things don't actually "dry" out.

yes, its hot and humid. i actually just visited a hydroponic farm in bangkok and noticed they run the pump on for about 4-5 secs and off for one minute. they were growing something that looks like swiss chard.

i'm planning to grow tomatoes so i'll have to play with it.

interesting that you say "Your plants will benefit the most by having their roots exposed to air in between nutrient-sprinkling sessions". the grow boxes i've seen appear to be air tight. should they have an air vent?

thanks, steve

Hi Steve
The best timing will depend on the pressure of your system and the plants themselves.
If it has reasonable pressure (60psi or over)generally you won`t need more than a second or two for the pulse and a minute or so for the pause.
If the plants need more water, its better to reduce the pause duration to generate more cycles.

Turning on a pump frequently will shorten the life of the pump dramatically.

Starting a pump from dead stop takes a lot of power/electricity.

You don`t want the pump to directly power the mistheads, it wouldn`t like turning on and off 60x an hour and the pressure would be all over :)
The way to do it is to use a diaphragm pump, a large accumulator tank and a solenoid valve controlled by the cycle timer.
The pump only runs when the tank pressure drops to 60psi and automatically cuts out at 80psi.
How frequently it runs depends on how many mistheads you have, the capacity of the accumulator tank and the working pressure of the system.
If you have a drawdown of 10gal and 40 mistheads,the pump will only run for 10 minutes every 4 hours or an hour a day.

A 12v 9Amp 100psi diaphragm pump would consume about 108w per day (9Ah)so it could even be battery/solar powered :)