Jacks 321 vs Masterblend/Calnit/Epsom salt analysis and questions

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Dredd

Dredd

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1
Hello everyone,
as someone that has been using Masterblend for years now with great results i decided to deep dive into the nutrient composition of both Masterblend and Jacks, both well known brands and i was wondering if anyone knows if theres any real difference between these two brands final recommended combinations, when i look at the nutrient breakdown on Jacks 5-12-26 formula:
Cropped


and on Masterblends 4-18-38:
Jacks 321 vs masterblendcalnitepsom salt analysis and questions


it seems like Jacks 5-12-26 is basically just Masterblends 4-18-38 with added magnesium sulfate, to the point where Masterblend has its own 5-12-26 product that is just the 4-18-38 + epsom salt premixed in it and looks almost exactly like Jack's:
Mastercropped


since both these brands instruct the addition of the same amount of calcium nitrate theres nothing interesting there so i wont mention it going forward just assume i include it, what i do find interesting and where the differences show up is the addition of epsom salt (magnesium sulfate),

if you use Masterblends 4-18-38 they advise that you add epsom salt at a 2 to 1 ratio, for every 2 gram of masterblend 4-18-38 add 1 gram of epsom salt, or if you buy the premixed version of 5-12-26 you dont have to add anything besides the calcium nitrate,

on the other hand with jacks 321 setup, you start with the 5-12-26 that already has magnesium sulfate in it much like the premixed 5-12-26 masterblend only jacks has a tad more magnesium sulfate 6.3%/8.5% vs masterblend 4.1%/5.4% and on top of this they tell you to add even more magnesium sulfate at a ratio of 3 to 1.

So which formulation has it right? should i be adding more magnesium sulfate to my Masterblend 5-12-26 formulation similar to the Jack's ratio? and since the 5-12-26 formulation is just the 4-18-38 with added magnesium sulfate at a 2 to 1 ratio does this mean that the touted 12g/12g/6g per 5gal of water that MPHgardener made so popular on youtube all those years ago should have actually been 12g/12g/12g per 5gal? or am i just not reading this properly and its actually the same for both brands?

also both these brands recommend a ph between 6.4 and 6.7 and yet i've been told again and again that cannabis needs 5.8 or no higher then 6, any thoughts on this?

thanks :D
 
Last edited:
mistletoe

mistletoe

9
3
I wish you had gotten answers to all these good questions. I have the same questions.

1. Has anyone ever noticed Jacks 5-12-26 needing extra epsom? I'm confused how anyone could need more than the already high amount of Mg in 5-12-26 (~60 ppm). When I've asked the people at Jack's the guy admitted it was already high but said "We have found in our trials that the addition of Epsom salt was not completely necessary, but it did help improve growth." I don't want to leave improved growth on the table but I also don't want to add unnecessary PPM to my solution which the Epsom does. I see GreenGenes is just doing straight 3.6/2.4 in his latest grow (using LEDs also) on youtube and he pioneered the Jacks 321 popularity.

2. I'd love to hear people chime in on the pH question as well. Jack's always wants to be about 6.4-6.7 runoff in my plants and I have to add quite a bit of acid to my tap to get it down to the 6 range.
 
Last edited:
Beachwalker

Beachwalker

7,055
313
Hello everyone,
as someone that has been using Masterblend for years now with great results i decided to deep dive into the nutrient composition of both Masterblend and Jacks, both well known brands and i was wondering if anyone knows if theres any real difference between these two brands final recommended combinations, when i look at the nutrient breakdown on Jacks 5-12-26 formula:
View attachment 978857

and on Masterblends 4-18-38:
View attachment 978856

it seems like Jacks 5-12-26 is basically just Masterblends 4-18-38 with added magnesium sulfate, to the point where Masterblend has its own 5-12-26 product that is just the 4-18-38 + epsom salt premixed in it and looks almost exactly like Jack's:
View attachment 978858

since both these brands instruct the addition of the same amount of calcium nitrate theres nothing interesting there so i wont mention it going forward just assume i include it, what i do find interesting and where the differences show up is the addition of epsom salt (magnesium sulfate),

if you use Masterblends 4-18-38 they advise that you add epsom salt at a 2 to 1 ratio, for every 2 gram of masterblend 4-18-38 add 1 gram of epsom salt, or if you buy the premixed version of 5-12-26 you dont have to add anything besides the calcium nitrate,

on the other hand with jacks 321 setup, you start with the 5-12-26 that already has magnesium sulfate in it much like the premixed 5-12-26 masterblend only jacks has a tad more magnesium sulfate 6.3%/8.5% vs masterblend 4.1%/5.4% and on top of this they tell you to add even more magnesium sulfate at a ratio of 3 to 1.

So which formulation has it right? should i be adding more magnesium sulfate to my Masterblend 5-12-26 formulation similar to the Jack's ratio? and since the 5-12-26 formulation is just the 4-18-38 with added magnesium sulfate at a 2 to 1 ratio does this mean that the touted 12g/12g/6g per 5gal of water that MPHgardener made so popular on youtube all those years ago should have actually been 12g/12g/12g per 5gal? or am i just not reading this properly and its actually the same for both brands?

also both these brands recommend a ph between 6.4 and 6.7 and yet i've been told again and again that cannabis needs 5.8 or no higher then 6, any thoughts on this?

thanks :D
I've been using and loving masterblend for a couple years now interesting info thanks for posting this!
 
Frankster

Frankster

Never trust a doctor who's plants have died.
Supporter
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I've been using and loving masterblend for a couple years now interesting info thanks for posting this!
Same with me, I just actually looked this up, cause I was wonder which was a better bargain, so I like controlling my mag/sulfur actually, and I get it for $1, so masterblend it stays.
 
Elroyyboy

Elroyyboy

11
3
I just started using Jacks this run, 7 weeks so far, but my tap is 48-55 ppm and when I add and mix the Jacks it drops to 5.7-5.8.
 
plumsmooth

plumsmooth

273
63
I wish you had gotten answers to all these good questions. I have the same questions.

1. Has anyone ever noticed Jacks 5-12-26 needing extra epsom? I'm confused how anyone could need more than the already high amount of Mg in 5-12-26 (~60 ppm). When I've asked the people at Jack's the guy admitted it was already high but said "We have found in our trials that the addition of Epsom salt was not completely necessary, but it did help improve growth." I don't want to leave improved growth on the table but I also don't want to add unnecessary PPM to my solution which the Epsom does. I see GreenGenes is just doing straight 3.6/2.4 in his latest grow (using LEDs also) on youtube and he pioneered the Jacks 321 popularity.

2. I'd love to hear people chime in on the pH question as well. Jack's always wants to be about 6.4-6.7 runoff in my plants and I have to add quite a bit of acid to my tap to get it down to the 6 range.
I started a thread on this a while back. Rather it was a poll: Jacks Needs Extra Mag yes or no? My theory is that maybe Epsom is hard to dissolve quickly so they boosted it to account for this. I premix mine so that would not apply. Also more importantly I noticed the true recipe is closer to 3-2-.5 then it is 3-2-1. I think it is actually around 3-2-.64!
 
Peat_Phreak

Peat_Phreak

540
143
I don't use epsom salt with Jacks. The easiest Jacks recipe that works well is 5/12/26 and calcium nitrate in equal proportions.
 
mikeross

mikeross

444
43
I don't use epsom salt with Jacks. The easiest Jacks recipe that works well is 5/12/26 and calcium nitrate in equal proportions.

Maybe for veg but I increase the 5/12/26 throughout flower. End up peaking at a 4/2 ratio but 1/1 works very well in veg
 
CookiesLikeWhoa

CookiesLikeWhoa

220
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If you're cutting out the epsom salt in Jack's would you want to add another source of sulfur or don't bother? It seems like it's a significant source of sulfur.
 
I

Its420anytime

55
18
Beautiful buds, very tight

321 is easy as it gets, and slways ensure nutes are thoroughly mixed.
 
BehindEnemyLines

BehindEnemyLines

403
93
Does this apply to the Jack's 5-12-26 nutes I bought in May?
Yes.

I pulled that directly from Jacks website here: https://www.jacksnutrients.com/cannabis-hemp-schedules

The nutrient formula hasn’t changed. The schedule/feed rate has changed.

They don’t even display the old schedules people are still using. They tweak the formula as their understanding of the needs of cannabis changes over time.
 
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