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Everything posted by DaveFarkas

  1. My IBC aquaponics system has been up and running since May. I have 30 tilapia and have actively growing basil, sweet peas, watermelon, and cucumbers. The fish are happy (no deaths, or disease & they eat well). The plants are growing well & flowering, but once fruit develops (baby watermelons & cucumbers), they turn black, die, and fall off the vine - so there's no fruit. Yet the vine keeps growing & flowering & repeating the same thing. The leaves are dark green at the growing end, but toward the roots, the leaves turn yellow, then black and die (see pics). As I said the fruit is also dying. Is this a deficiency or disease? Using 3 different test kits I have, here's my latest parameters: Using API's Freshwater Master Test Kit: pH: 6.1 (using electronic meter) Nitrates: 40 ppm Nitrites: 0 ppm Ammonia: 0 pmm Using Nutrafin Test Kit: Phosphate: 0 (Low / Non-existent) Calcium: < 20 ppm (Low) Free Iron (Non-Cheleated): .1 (High) Free Iron (Toxic): 1.0 (High) Carbonate Hardness (KH): 20 ppm (Low) General Hardness (GH): 100 ppm (Moderately Hard) Using Rapidtest Soil Test Kit (so may not be accurate since I have no soil) Phosphorus: P3 (sufficient) Potassium/Potash: K2 (adequate) Nitrogen: N3 (sufficient) Just yesterday, I added some crushed shells in a mesh bag to the water to help buffer the pH and keep it up (had dropped to 5.7 some days). It should also help with the calcium. I also added some Maxicrop Liquid Seaweed which should help bring up the Potassium/Potash. To address the high iron, I am working on replacing the tank water over time. Any ideas what is going on & what else I should do to fix it? Thanks!
  2. Thanks for the reply. No I still don't know why the fruit on my plants (both cucumbers and watermelons) turn black and die. It's still happening, but with new shoots. I don't have a dedicated aeration pump. The water pouring back into the tank causes quite a disturbance with air bubbles forming deep into the water, so have not had any issues with oxygen. No fish have ever died, so I assume there is plenty of oxygen in the water, though I've never tested it (and don't know how to). My pH is currently 5.9 so going down. I've recently added a bag of seashells, but it's still staying low. How do you suggest I raise it?