Dry Yellow Leaves

[Tom Oliphant]

Dear Friends,

I got my system (Aqua Abundance, 2 media and 1 DWC, with a 500 gallon fish tank) eight months ago. I believe it is fully cycled because the ammonia is a 0.5 ppm, the nitrite is at 0.0 and the nitrate is over 160 ppm. I add a tablespoon of iron every month or two and I add a tablespoon of micronutrients at about the same rate. The pH has stabilized at 7.4 according to a gauge I bought and calibrated to a known pH level of 4.0. The test chemicals I got from The Aquaponics Source shows the pH to be stable at 6.8. Everything was going fine until I closed up my 24 foot diameter geodesic dome because of cold temperatures. I am in the process of buying a CO2 meter but I think I may have a problem. The leaves are yellow, dry, and withered. I don't see any aphids and I have looked closely and I know what they look like from other outdoor plants last summer.

I have attached some pictures below.

I am looking for hints as to the cause and possible cures for my problem.

Thanks for your help.

Tom Oliphant TVO >:)

[Jeff S]

I sympathize with you Tom. My system worked great for a year or so then I started having the same problem. I had the water tested  at the local university and found everything on the high side as far as nutrients. The thing that stood out was high Chloride and sodium readings. Turns out my ground water is high in chlorides so I'm assuming that's where the problem started. NOt sure if that was all the problems. Also my roots were pitiful looking. Even healthy plants that I transplanted withered and died.  Things are looking better now after multiple 50% water changes. 

[Tom Oliphant]

Dear Jeff,

Thanks for your response.

I have a current copy of the local city water quality report. It says that the only thing the city adds to purity the water is Chlorine. Eight months ago I bought a Chlorine filter from Amazon and installed it on the water line I use for all water purposes under the dome. I believe it should last me a year and then I will replace it. I measure my Total Dissolved Solids (TDS) and I hover around 220 ppm. I measure the tank Electrical Conductivity (EC) and I hover around 430. I am sure of the total significance of TDS and EC but since they are stable I am not too worried. I also track all the water I take from the system and add to the system. This is how I prove to myself that I am trading out fertile water with city water. 

I don't know what other impurities I should be tracking.

What I have done is open the windows for six hours every day and all the plants are greening up and staying hydrated. I won't know that this is the primary cause until I receive my CO2 meter in the mail this week. I'll let you know how it goes. I believe that CO2 plays a great role in plant health because it is what the plants need to breath. I just didn't know how important it is to provide it on a daily basis. I have resisted adding a CO2 generator to my dome because I don't want to penetrate the insulated wall for the gas line and the penetration of the Solex panel above for the exhaust tube.

TVO >:)

[Jeff S]

My GH is screened in the summer and I use a wood burner in the winter. I never worried too much about co2. I'm no expert but 220 TDS is low. I know in hydroponic setups they run 800-1200. Why do you get 2 different readings on your PH? I use the API test kit for water testing. If you've never watched the Bright Agrotech video series on nutrients and water quality I'd highly recommend them on YouTube. 

[Tom Oliphant]

Thanks for the video suggestion. Can you give me a URL? My TDS and EC are increasing every time I take a measurement. They have not stabilized yet so I will wait and see. My 24 diameter geodesic dome has four windows and a double door and everything it great during the summer. It is during the winter with cold temperatures when it is closed up tight that I seem to have had a problem. Now I open it some every day and the new leaves are not exhibiting the yellow and dryness. As the old yellow ones die I pull them off and put them into compost. My CO2 meter should arrive today. I will let you know what it tells me.

TVO >:)

[Jeff S]

This is the complete nutrient list:  https://www.youtube.com/playlist?list=PLAPahqrfGZZmLPh4vXzRDqWrXP7L...

Search "CO2 Bright Agrotech" on YouTube and you'll get all you need to know on CO2

Nate is educated on what he tells you. There's lots more on their YouTube site to see. 

You may want to concentrate on your NPK. You could use Potassium Sulphate without raising your ph. All this is covered in the videos.

[Tom Oliphant]

Dear Jeff,

Thanks again.

TVO >:)