MAKING MY OWN CNS 17 (help needed)

so i love the results of cns17 grow by botanicare, i don't like the fact that i can't use it in my dosatron because its a suspension not a solution, and it clogs the filter and abrades the seals and interior of the injector.

so my goal was to create a two part fertilizer with the same profile, 3-1-2-3.6 N-P-K-Ca, as the botanicare.


what i need help with is my math, if someone who has done this before could just double check my math it'd be much appreciated.

here it goes.

botanicare 3-1-2-3.6 (N-P-K-Ca) 9#/gallon

Nitrogen
9*.03=.27#N/gallon

Phosphorus(P2O5)
9*.01=.09#P2O5/gallon

Potassium(K20)
9*.02=.18#K2O/gallon

Calcium
9*.036=.324#Ca/gallon






so using calcium nitrate 15.5-0-0-18 at 1.8#/gallon gives me
1.8#*.155=.279#N/gallon

1.8#*.18=.324#Ca/gallon


using jr peters 5-12-26-0 at .68#/gallon gives me
.68#*.05=.034#N/gallon

.68#*.12=.08#P2O5/gallon

.68#*.26=.177#K2O


so by my math i need to add .68# or 309 grams of 5-12-26-0 to a gallon of water

and 1.8# or 817 grams of 15.5-0-0-18 CaNO3 to another gallon of water to create my two parts, then use them in equal proportions.

so as a partial confirmation without sending the results to a lab for an elemental breakdown i mixed a test batch to compare EC once mixed.

20ml of cns17 in 1 gallon tap water(90ppm or .18ec) resulted in a final solution of 950ppm or 1.9ec

20ml each of my a&b concentrates in 1 gallon of tap water resulted in a final solution of 900ppm or 1.8ec.

thats an ~5% discrepancy but that could be because of minor inaccuracies in measurement of both the gallons of water and fertilizer additions and also the 5-12-26,the way its currently mixed, has a bit less P2O5 and K2O than the CNS and i never checked the micros.

I think the issue you'll run into is that what is on the CNS17 label is only the guaranteed minimum. There is inevitably more in the bottle than what is listed. You might need to step up both solutions 5-10% more than the labels to get a better match.

There are also a few other ingredients in the CNS17 (chelates, amino acids, and trace minerals) that are going to have an impact on how the nutrient programs compare. The chelates especially due to making the elements available at a broader pH range. You may find less stability with the Jr. Peters and need to be a little more diligent with the calibration of your meter and testing of the nutrient solution to make sure uptake isn't impeded.

Your math looks good btw. I use a ppm conversion rather than a weight conversion, but it all get's us to the same place.

3-1-2 3.6/0.5 @20ml per gallon:
Nitrogen ~ 159 ppm
Phosphorus ~ 24 ppm
Potassium ~ 88 ppm
Calcium ~ 190 ppm
Magnesium ~ 27 ppm

So that's the profile to match. Lot's of ways to get there.

Running a 15.5-0-0 18/0 @ 4g per gallon:
Nitrogen ~ 164.3 ppm
Calcium ~ 190.8 ppm

Running a 5-12-26 @ 1.5g per gallon:
Nitrogen ~ 20 ppm
Phosphorus ~ 21 ppm
Potassium ~ 86 ppm

This puts the total for the custom system at-
Nitrogen ~ 184.30 ppm
Phosphorus ~ 21 ppm
Potassium ~ 86 ppm
Calcium ~ 190.8 ppm

The Nitrogen gets about a 15% bump up. You might want to consider a pinch of a PK booster in that solution to reduce the Nitrogen without hurting the PK levels. Running 1g per gallon of the 5-12-26 and ~0.125g per gallon of a monopotassium phosphate (0-52-34) should balance that solution a little better for veg. Then you have the third part you'd need to take the solution into bloom by just upping the MonoPoPhos (2x-5x more) and reducing the Cal-Nitrate (about 1/2 strength).

thanks for the input!

i figured the increase in N was the type of CaNO3 used, and obviously there's a difference in the 5-12-26 that leads to a bit more N.

WRT the chelates and micros, the 5-12-26 has all the standard chelates and micros any typical bottled fertilizer would have, though it does lack the amino/carb base that makes CNS17 unique. Either way ill be monitoring plant health closely.

I've been really disappointed in the JR peters mixed to the directions in peat, and looking at my calculations it makes sense, by directions its 800grams CaNO3 in one gallon and 1200grams base in one gallon then used in equal volumes. thats nearly 4 times the amount of base needed, id have to use the CaNO3 stock solution at 4-5 times the rate of the base in that scenario.