Rotting Roots

I grow in a 6′ x 5′ area using two 1000-watt HPS air-cooled lights. I use a 40 site aeroflow system. Water temp: 80 degrees. Room temp 85 degrees. One day I went to check my plants and what were healthy lush white roots had become a brown mushy mess. Thick gelatin goo formed everywhere, binding the roots together.
I cleaned the system twice using bleach and pool shock, thoroughly rinsed and the same problem persists. I add a few drops of food grade hydrogen peroxide per gallon every day.

I use the same plants, clones started in one-inch rockwool cubes. I pulled all the damaged roots and dipped each plant in Flora Shield. The water currently appears to be fine. Normal algae buildup appears in the tubes and reservoir. I use fresh air drawn from a lawn-level vent routed under my house to a basement grow room. Am I bringing in critters from the lawn? Is my rockwool tainted with pithium or the like and nothing I can do will kill it?

Torrance, California

Both the air and water temperature are the problem. At 80 degrees, even in an aeroflow system, the water has little ability to hold oxygen in solution. The result is an anaerobic micro-environment: the roots are deprived of oxygen, weakened and susceptible to attack by bacteria.

The high air temperature strains the plants further, increasing their metabolism, their water and nutrient needs, and stressing the roots to work harder.

Lower the temperature using ventilation or air conditioners so that it is no higher than 78 degrees. The water temperature should be kept at about 72 degrees. An aquarium-grade water chiller can be used to cool the water. At 72 degrees, the water still has the ability to hold substantial amounts of oxygen.

Once the water temperature is lowered, the roots will have access to a lot more dissolved oxygen, which they require to respire. This will encourage healthy root growth. Lowering the air temperature should solve your root problems. It will also slow plant metabolism, enhance the plants’ growth rate and ultimately, increase yield.

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