Ask Erik

Stressed,
Let’s hope we can have your pen name changed to “stoked” next time you write back by solving these issues that you are describing. Temperature is always a big factor, and is especially critical in hydroponics. Before when you were using a “sterile” nutrient solution from chemically derived nutrients, you may have been on the threshold of problems, but were lucky enough to avoid them. The high level of aeration coupled with the sterile nature of synthetic nutrients might have been just enough to keep pathogens away and nutrient availability to your plants intact.

With organics, while a portion of the nutrients are available directly to the plant, there will be a portion that is being supplied as “raw,” requiring microbes, etc. to convert the cruder forms of nutrients into forms that the plant can easily take up. In a soil or soilless growing medium, the microbes required to accomplish this have plenty of “space” to live. Since there is very little growing medium in your system, the microbes required for these important conversions can only try and live in the solution, on the inner sides of the bucket and directly on the roots. This means that some of the species that are important in converting organic matter to plant food might not have a place to live. Remember that these organisms for the most part, evolved in growth mediums (soil), not water; so that’s the type of environment they prefer.

You are supplying the microbes with plenty of oxygen from your high-powered air pump. This is causing a population explosion in the species that are able to thrive in the watery environment, while the solution, growth medium, roots, etc. may be lacking other species because it is not a conducive environment for them to multiply in and perform the necessary functions. Basically, you may have wound up with a microbial imbalance which in organics can equate to a nutrient imbalance. The warmer temperatures and raw, undigested materials can create a situation where pathogens may develop, and in severe cases cause root rot.

The constantly rising pH may be indicative of a microbial population explosion from the abundant food sources combined with high levels or aeration. Unfortunately, it appears that this has become an unbalanced population in terms of the species diversity. The additions of substantial quantities of chemical or organic pH down products can in fact create nutrient imbalances. If using chemical pH control products at significant levels, the microbial populations may suffer, furthering imbalances in the species diversity.

Aside from recommending a nutrient system better suited for your DWC methods, I can advise the following:

• reduce the level of aeration
• include a broad spectrum of digestive enzymes in your feeding program
• occasionally re-introduce balanced microbial populations by adding well formulated beneficial inoculants at half strength
• reduce the level of carbohydrates and other potential food sources for microbes that you have been adding
• ensure that the nutrient you are using is not too “thick” and does not contain excessive levels of undigested organic materials
• be sure to completely empty the buckets out once per week and start with fresh solution; you may find that doing this even more frequently will have a positive effect.

Hopefully, this will get things back on track, and I admire that you have been willing to experiment in an attempt to improve the quality of your harvests.

Highest Regards, Erik Biksa