phxazcraig
- 543
- 93
Just a month into my first crop with coco and fertigation, and I'm trying to understand the water chemistry better.
One specific question I have is in regards to a feeding chart (Fox Farms hydro chart in this case) that lists desired PPM and EC limits. Doesn't matter what they are in this question.
My chart says PPM in week three should be up to about 1050-1190 ppm, and an EC between 1.5 and 1.7. I'm assuming these are maximum limits.
My question is "Do I adjust to the limit of EC, or PPM, or whichever is higher?" My EC is much higher than PPM. That is, when I finish mixing my nutes I have an EC under 900, but EC at 1.9.
I'm assuming I ignore the PPM reading, and add RO water until I get the EC down to the upper target limit of 1.7.
Here's what I'm doing.
OK, so I start with 10 gallons of RO water, PPM 20 or less. I add my Silica and wait an hour, then cal/mag. I add 2.5ml/gallon, as directed. I note that PPM jumps to 300 at this point.
Next I add my nutes, which for now are Big Bloom and Grow Big Hydro. After the Grow Big, my PPM hits 800 or so and my EC skyrockets to around 1.9 And my pH drops like a stone to about 4.6. I don't think the remaining chemicals change the PPM or EC much.
Next, a dose of Humic Acid (Diamond Nectar), and a sprinkle of Yucca Powder.
At this point my pH is very low and I add some pH UP to bring it up to 6.0 or 6.1. (Once I dump it in the reservoir a Bluelab controller keeps the pH down to 6.0.)
It is at this point that I adjust the EC by adding a gallon or so of RO water. EC drops from 1.9 to 1.7, and PPM goes down to 860 or so. That gives me another 200-300 ppm to play with, but no EC room.
One specific question I have is in regards to a feeding chart (Fox Farms hydro chart in this case) that lists desired PPM and EC limits. Doesn't matter what they are in this question.
My chart says PPM in week three should be up to about 1050-1190 ppm, and an EC between 1.5 and 1.7. I'm assuming these are maximum limits.
My question is "Do I adjust to the limit of EC, or PPM, or whichever is higher?" My EC is much higher than PPM. That is, when I finish mixing my nutes I have an EC under 900, but EC at 1.9.
I'm assuming I ignore the PPM reading, and add RO water until I get the EC down to the upper target limit of 1.7.
Here's what I'm doing.
OK, so I start with 10 gallons of RO water, PPM 20 or less. I add my Silica and wait an hour, then cal/mag. I add 2.5ml/gallon, as directed. I note that PPM jumps to 300 at this point.
Next I add my nutes, which for now are Big Bloom and Grow Big Hydro. After the Grow Big, my PPM hits 800 or so and my EC skyrockets to around 1.9 And my pH drops like a stone to about 4.6. I don't think the remaining chemicals change the PPM or EC much.
Next, a dose of Humic Acid (Diamond Nectar), and a sprinkle of Yucca Powder.
At this point my pH is very low and I add some pH UP to bring it up to 6.0 or 6.1. (Once I dump it in the reservoir a Bluelab controller keeps the pH down to 6.0.)
It is at this point that I adjust the EC by adding a gallon or so of RO water. EC drops from 1.9 to 1.7, and PPM goes down to 860 or so. That gives me another 200-300 ppm to play with, but no EC room.
