Watering flood systems

I am planning to set up an active flood system. Should I keep water running constantly through the system, or should the water run intermittently, regulated by a timer? If so, what’s a good cycle for the timer set-up? Do you have any recommendations on a nutrient solution for this system?
Tommy Two Toke,

The watering regimen depends on many factors: the planting medium, plant size, the light reaching the plants, temperature and humidity.

Some mediums hold more water than others. For instance, small plants growing in rockwool blocks or slabs are usually irrigated one to three times a day. However, if the same size plants were growing in grow rocks they would be irrigated three to five times daily. As the plants grow they use more water and require more frequent irrigation.

Light equals energy. The more light the plants are exposed to, the faster their rate of photosynthesis and the more water they use. When the temperature is above 26 C (80 F) plants use transpiration to keep cool. This can use water at a fast rate. The less humidity, the less evaporation from both the medium and the plant.

All of the commercial hydroponic fertilizers work. The problem is which works best in a particular situation. Take advice from your garden shop as well as from friends who have grown successfully. Don’t be afraid to try out fertilizers on a few plants.

Readers with grow questions (or answers) should send them to Ed at:
Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA
You can also email Ed at [email protected], and send queries via his website at www.quicktrading.com.
All featured questions will be rewarded with a copy of Marijuana Question? Ask Ed. Sorry, Ed cannot send personal replies to your questions.