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Water Soluble Questions

How much fertilizer do I put in my stock tank with a injector?

This depends on a few things: 

  • Whether you have a fixed injector or one that can be changed 
  • What PPM (parts per million Nitrogen) you want to be feeding at
  • Use the Charts below to decide how much grams/L to use 

For any fertilizer that has 20%N(20-8-20, 20-20-20 etc.) (grams/liter of concentration)

Injector Rate

100ppm

150ppm

200ppm

250ppm

300ppm

350ppm

400ppm

1:200

100

150

200

250

300

350

400

1:150

75

112.5

150

187.5

225

262.5

300

1:128

64

96

128

160

192

224

256

1:100

50

75

100

125

150

175

200

1:50

25

38

50

62.5

75

87.5

100

 

 

For any fertilizer that has 15%N (15-15-30, 15-30-15 etc.) (grams/Liter of concentration)

Injector Rate

100ppm

150ppm

200ppm

250ppm

300ppm

350ppm

400ppm

1:200

133

200

260

333.33

400

466.67

533.33

1:150

100

150

200

250

300

350

400

1:128

85.33

128

170.67

213.33

256

298.67

341.33

1:100

67

100

133

166.67

200

233.33

266.67

1:50

34

50

67

83.3

100

116.66

133.33

 

How do I figure out what rate I need for different injector ratios?

There is a equation that you can use to figure out any rate for any injector or fertilizer. 

X = (Desired ppm x Dilution Factor)/ (Percent Nitrogen x Conversion Constant) 

  • Desired ppm = What you want to be feeding at 
  • Dilution Factor =  the biggest number in your injector rate (Ex, 1:200, Dilution Factor is 200)
  • Percent Nitrogen = The first number in your fertilizer (Ex. 10-52-10, Percent Nitrogen in 10)
  • Conversion Constant = Different depending on what you are trying to figure out. See the Conversion Constant Chart below 

Conversion Constant by Measurement Units

Units

Conversion Constant

Ounces of fertilizer per gallon

75

Pounds of fertilizer per gallon

1200

Grams of fertilizer per liter

10

 

Example

How many grams/L would be needed to get 300ppm if I have a injector ratio of 1:250 using a 10-52-10 fertilizer 

 X = (Desired ppm x Dilution Factor)/ (Percent Nitrogen x Conversion Constant)  

Desired PPM = 300

Dilution Ratio = 250

Percent Nitrogen = 10

Conversion Constant = (Use chart on bottom of page) Grams/L = 10 

X = (300 x 250) / (10 x 10)

X = 75,000/100

X = 750grams/L of stock solution  

What is Electrical Conductivity and do I need to know about it and will it affect my plants?

Electrical Conductivity (E.C) is the measure of total dissolved salts in a solution, the factor that influences a plants ability to absorb water as well as nutrients. So yes, it is very good to know what it is. It is a very easy way to measure fertilizer level. Every fertilizer should have a Conductivity Chart showing what the EC is at various PPM. Water in general has a E.C Value. So to check what value your E.C is giving you check the water that is coming into your greenhouse and get a E.C. and then check what the EC is after you add fertilizer to it. Subtract the first E.C and then verify it to the chart to show you how much fertilizer you are adding to the water. Below is the Conductivity Chart for our Water Soluble products.  Every fertilizer is different. Omex has very low salt in their fertilizer which makes it beneficial to your plants.

 

Conductivity Chart (mmhos)

 

20-20-20

15-30-15

15-15-30

20-8-20

100ppm

0.41

0.6

0.53

0.48

150ppm

0.61

0.88

0.77

0.7

200ppm

0.82

1.16

1.05

0.95