This is my third grow using Jack’s 321 which I love. But I’m getting tired of measuring the grams. So instead of grams I use teaspoons which breaks down as:
For 3.2 grams I use 5/8 tsp (1/2t +1/8t) = 3.375 grams
For 2.4 grams I use 1/2 tsp = 2.5 grams
For 1.1 grams I use 1/4 tsp = 1.25 grams
Do you think this OK? Each part is slightly higher but not by much.
Thanks for responding!
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Part A should be 3.6 gr.
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Part A 3.79 Part B 2.52 epsom salt .99
Overall Jacks is very forgiving so if you are a touch over probably no issues just watch the plants.
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I assume the chart covers soil or hydroponic?
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Jacks works in a number of ways, and is versatile. Dry fertilizers often request weight and not volume, because if moisture gets introduced the weight can change while maintaining the same volume. Consistency does matter, too much of one thing can throw something else off. Either increase demand of another causing deficiencies, or completely lock out another
I’ve done 3/2/1
3.6/2.4/1.2
3/2
4/2
4/2/1
They can all be used effectively if the PPMs and pH remain constant and appropriate overall for the chosen grow method.
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I adjust my strength of feeding all the time. As long as you keep the same ratio you’ll be fine. You can play with the ratio a bit at certain points of the plants life but id say thats optional and you should make sure you are comfortable with your nutes before you do that. Thats why i love jacks, alot of versatility.
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Thanks that what I like to hear!
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If I recall, member @Spiney_norman measures his jacks w/teaspoon measurements also.
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1 tsp=5g
1/2 tsp=2.5g
1/4 tsp=1.25g
I too use volume because im too cheap to buy a gram scale.
Note: these are rounded down to simplify things
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I still weigh it out using triple beams! I got a certified set of weights (1, 2, 5 and 25 grams) that I use every time I mix fertilizer. I’ll mix 2, 4 or 6 gallons of fertilizer each time depending on the number of plants… Takes me only 1 hour to mix/water each morning.
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Thanks for pointing it out 3.6 for part A. I’ve modified accordingly:
For 3.6 I use 3/4 tsp = 3.75 grams
For 2.4 I use 1/2 tsp = 2.5 grams
For 1.1 I use 1/4 tsp = 1.25 grams
Looks better anyway.
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Thats my thinking as well!
Friends,
If you go to the Jack's website and download each product's material Safety Data Sheet (SDS). Look under Section 9: Physical and Chemical Properties, you will see the Relative Density (RD) for their products is stated as 55 - 75lbs/ft^3 which is a huge manufacturing variation. I did the math to show the weight variation for one teaspoon below:
@ 55lbs/ft^3: 1 tsp weighs 4.3grams
@ 65lbs/ft^3: 1 tsp weighs 5.1grams
@ 75lbs/ft^3: 1 tsp weighs 5.9grams
That’s 1.6gram error per teaspoon! I contacted JR Peters regarding RD variation, and they replied that you should add their products by weight, and not volume to avoid any discrepancies. This is an awesome company, I emailed them about this, and they responded in 20 minutes. I just can’t say enough good things about them.
Happy growing 
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Thank you @Harold for going the extra mile. Thats good to know. Interesting variance.
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i use a slightly rounded tsp of A, after its dissolved then the same amount of B
No longer use Epsom, just a tad more of A by rounding the teaspoon does the job.
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Does that work with both parts A and B?
I think @Spiney_norman just answered my ? Guess I didn’t read down far enough. I might turn a couple of measures on the lathe and calibrate them to parts a and b to be exact. Might do a 4/2 also. I’ll post them up when I get a chance to make them. Hmmmmm, mabey there’s a market there, set of three engraved for a,b, and epsom. Just dip, card off level and pour, no more weighing!
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I did exactly that for mixing 5 gallon batches…
Took a pill bottle like this…
Set it on my scale and zeroed out the weight, then filled to the desired weight of food. Then I marked the level and cut it off with a hacksaw. Glued it to a popsicle stick and it was good to go. Made one for each ingredient. Easy. .
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That sounds like a good invention, if you get it figured out let us know. I’ll be looking for it on the market! No more measuring yay…
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That’s a good idea, but I don’t need that much mixture. But it gets me thinking of making my own tool.
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