I set up a deep water system (with bubblers) for a friend. Nine tubs with a total capacity of 150 gallons. I used MaxiGro 10-5-14 to get started while waiting for my order of a two part nutrient package from American Hydroponics to arrive.
The MaxGro resulted in a ppm of slightly over 900 in all tubs. This is with water that has a ppm of 231 to 278 and a ph of 7.2. The pH of the solution ranged from 5.87 to 6.12. Solution temperature reaches 80 degrees F (it's hotter than hell here), and this is an outdoor installation under shade cloth. The crop is strawberries, so the pH is correct.
But now, four days later, the solution ppm has dropped to 108 to 130 in five tubs. I can see the precipitate on the bottom of the tubs. The pH remains unchanged.
Strangely, the ppm in the remaining four tubs remains at around 900. Same water, same amount of nutrients. No sign of precipitate. I'm having trouble wrapping my head around this.