Making your own masterblend proxy from scratch (DIY)

In this video, we show you how to prepare a concentrated solution that reproduces the mineral composition you would get if you dissolved 20g of masterblend 5-11-26 and took it to a final volume of 250mL using distilled water, assuming the label of the masterblend exactly describes its mineral composition. This solution can be used as the 5-11-26 mixes provided by masterblend, JR peters, Jacks, etc.

Note that this is not guaranteed to reproduce the exact composition of any of the commercial 5-11-26 mixes, in that we don't know the exact chelates, additives or other substances used in their making.

Solutions of this type are commonly used with Calcium Nitrate, Magnesium Sulfate and/or Monopotassium phosphate, depending on the plants being fed. Note that Calcium Nitrate should always be used, as this solution provides no Calcium and only a small amount of nitrogen as nitrate.

When used at 10mL/L (37.85mL/gal) it provides the following final composition (in ppm):

N (NO3-) 43.372
K 171.452
P 39.926
Mg 24.88
S 34.559
Fe 2.4
Mn 0.4
Zn 0.12
B 0.4
Cu 0.12
Mo 0.08

The solution (250mL final volume) is prepared using the following chemicals (in grams):

Copper Sulfate (pentahydrate) 0.012
Iron sulfate (anhydrous) 0.163
Magnesium Sulfate (Heptahydrate) 6.308
Potassium Monobasic Phosphate 4.386
Potassium Nitrate 7.826
Zinc Sulfate (Monohydrate) 0.008
Manganese sulfate 0.028
Sodium Molybdate (Dihydrate) 0.005
Boric Acid 0.057
Disodium EDTA 1.8
Sodium Benzoate 0.05
Green Food dye 1 drop

Please bear in mind that the exact salts above should be used. Adjustments need to be made when the degree of hydration of the salts does not match the example. For example, if you do not find anhydrous iron sulfate but, iron sulfate heptahydrate, you will need to adjust the amount accordingly. If you need help with any such adjustments, please leave a comment below.

Here are some of the glassware and scales used in the process:

(Please notice that the Amazon links below are affiliate referral links. This means that if you click on them I may receive a commission from purchases. There is no additional cost to you, but it helps me to keep posting content for free.)

Class A Volumetric Flask (250mL)
https://amzn.to/3jME8WI

Beaker set
https://amzn.to/3lwdGkw

Recommended scale for larger weights (+/-0.01, 500g max)
https://amzn.to/2GVBrTW

Recommended scale for smaller weights (+/-0.001, 50g max)
https://amzn.to/37gpWAy

Magnetic stirrer
https://amzn.to/3ifEgzA

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