Aeroponic Blues

My son and I built a 30 plant aeroponic system using the directions contained on your website. We built 5 tubes using 4" pvc pipes. Inside each we installed 1" pvc and drilled the small holes per your instructions. We acquired a 30 gallon nutrient bucket and built 2 pvc manifolds for use with a 1250 GPH pump. We filter pump input using a rock/charcoal homemade filter and the drain into the reservoir. We are using a 400 watt magnetic ballast (1000 watt equivalent) grow light. A local PhD sold us bat guano, flora nutrients, calcium/magnesium, H2O2, and we also have nitrogen, growzyme, and pythoff. We buy deionized water.

We acquired a variety of heirloom seeds (tomato, peppers, lettuce, celery, cucumbers, English peas, etc. All seeds are organic and most have a lineage of at least 50 years.

So we plant seeds either on cheesecloth or clay pebbles) in 3" pots. The seeds sprout and grow rapidly to a height of 2". After a few days out nutrients turn darker and plant growth comes to a halt. System develops pythium and we fight back with pythoff but so far continue to loose plants to root rot over and over. Have tried varying pump run times ranging from 10 sec on/4 min off to 2min on/30 min off with no change in results.

After 2 months we are no closer to having anything growing than we were after first couple of weeks. We must be doing something wrong but cannot determine what. Suggestions would be sincerely appreciated!

In my experience, once pythium is in a system you can bet every single plant has already been infected. Particularly in a hydroponic or aeroponic system, which tend to recirculate the water. I entertained the idea of trying to finish a few gardens out before, and the results have never been pretty. Prevention really is the key, and on that note I do have some tips that should help make your next attempt more successful.

I hate the thought of the bat guano introducing bad micro-organisms to your setup, but is is a small possibility. The possibility is greater if the guano is used straight.....the possibility is less if you are brewing a compost tea, then using the compost tea in your hydroponic system.

As far as the contents of your nutrient reservoir are concerned, a great many things can be done improperly that end up stressing out or harming plants. I don't know your exact level of experience, and I don't know exactly what your nutrient management strategy is....let me just say that sometimes simple (and less) is better. That is especially true if this system would be your first successful venture into hydroponics.

If you begin to have the suspicion that something in your feeding plan may be part of the problem, here is my advice. Use a basic, high quality three part hydroponic nutrient....one of my favorites is B.C. Nutrients. Use it at quarter strength of the recommended full strength. On a TDS meter this would probably be about 300 or 400 ppm. Add half the recommended B1....like Thrive Alive B1. That's it.

Top the water off once a day. After that, check and adjust the nutrient strength once a day. After that, check the pH and adjust it once a day. After two weeks of maintaining the same nutrients, dump them and start with fresh water and nutrients.

With a plan and maintenance like this, at least you know the feeding is not killing roots, (or anything else killing roots) causing them to rot in the water, in turn inviting pythium and other things.

Now let's talk a little more about prevention.

Fungus gnats are a major vector to carry the pythium spores to the roots of your plants. Make the system gnat-proof as much as possible. Tighten up spaces where plants sit in the system. Pantyhose can be used if needed. Eliminate gnats from the grow environment by taking out the garbage frequently. Don't leave fresh vegetable scraps around (very hard if you compost). Don't allow algae to grow in the hydroponic system (eliminate light from coming in contact with the nutrient solution as much as possible).

Eliminate the pythium spores from the environment. This means cleaning the hydroponic system very, very well with a 5% bleach solution or a hydrogen peroxide solution....and also as much of the house as you dare to. Any dust from the walls, door jams, window sills. Definitely don't let the dog (if you have one) into the garden room. Spraying any black mould or damp areas with a bleach solution.

Very particular gardeners sometimes refuse to go into their garden until they have had a shower and a fresh change of clothes (if they have been outside). I've never gotten that crazy....but I sure considered it after having mites in my garden! Had to empty the whole room and let it sit empty for 3 months to finally get rid of them!.

So let's see where we are....tighten up any human behavior that might be stacking the deck against your plants. Eliminate main vectors. Eliminate spores....oh yes, one more thing on eliminating spores. You can run a negative ion generator or air purifier, or HEPA filter the home air (yes, I know, probably not the most economical solution here).

And, finally, for the spores that inevitably persist in your environment....

Keep at least a pre-filter on the air in for the garden.

Keep the physical conditions in the grow room un-friendly to bugs like pythium. Specifically this means putting a thermometer in your nutrient reservoir and trying to keep the temperature of the nutrient solution between 58 degrees and 70 degrees. I would also advise keeping the nutrient solution highly Oxygenated, but that should not be an issue given the hydroponic system you are using. The air in the grow room should be kept on the cool and dry side....65 to about 72 degrees would be ideal (but nearly impossible without a good source of cold air lol).

If you are confident in your feeding and maintenance of the nutrient solution, it may just be a matter of doing some cleaning, keeping everything a little cooler the next time around, and everything could go good for you. No matter what, the hydroponic system itself needs to be cleaned VERY WELL before it is reused....the same goes for anything that came in contact with the contaminated water (the water pump, netted pots, expanded clay pellets). Make sure you soak clay pellets very good (3-5% bleach) or they will re-contaminate everything.

And just one last bit of advice. The addition of Silica at about half the recommended strength on the bottle will fortify and bolster the immune system of your plants....it really is amazing stuff....a crystalline matrix inside the plant tissue that makes them physically stronger as well as very disease resistant and stress resistant. Silica is one of 3 must-have nutrient additives that I recommend new hydroponic gardeners begin using (slowly) once they have success at least once using only the three part hydroponic nutrients by themselves.

I sure hope this helps you out Jason, and HAPPY GROWING!