We are constructing hydroponic salad production in Iceland. We use trays and watering systems to water plants and seed to full grown plant for 36 days. We change trays for spacing three times . Do we need to use drain and constant running water for oxygen or can we water the roots and /or overhead spray without having foul water and harvest quality plants? All trays are sterilized after each twelve days run.
Cleanliness and maintenance are keys to any hydroponic system. Also plants need oxygen to their roots. What type of system are you running? Ebb and flow, NFT, drip, float, aeroponic? I have noticed I can maintain a reservoir for longer periods of time in more oxygenated systems. In a deep water culture system that also circulates I have been able to maintain my res for about 21-28 days. I still had to adjust pH and top off the water level. I had no foul odors or diminished quality in harvest. The only issue is adjusting ppm/EC for the age of the plants in the system. For instance a plant that is 4 days old does not need the same nutrient levels as the plant that is 28 days old.
I am also a big fan of using beneficial bacteria and fungus in my root zone. Usually foul odors are due to some negative bacteria or root rot! Check out House and Garden Root Excelurator, this product is not only a root stimulant but also cures root rot. I hope this has helped and please email or call any of our locations when you have any questions.