Who uses Jack's 321 in RDWC?

Am contemplating buying 25# bags… currently using (and happy with) GH Flora trio, etc., but Jack’s would be cheaper.

Who uses Jack’s in RDWC? What nutrient schedule do you use?


@Graysin @HappyHydroGrower both use Jacks with great results


Thanks for the tag @CooterJuice

Yep! Sure do. I use Jack’s at 3.6/2.4/1.2, sometimes I adjust the Epsom up to 1.5 if my ladies are really magnesium hungry (usually in flower). Sometimes I’ll adjust but honestly I rarely do.

@Hellraiser and @Nicky also use Jack’s - granted they’re using autopots and coco coir, but as far as I’m concerned the results are substantially similar and concerns about mucking up your water lines are the same. So they will have good advice too.


Yeah Jacks would be great for hydro, cheap and works just as good as much more expensive nutes.

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You’ll be happy with Jack’s, highly recommended the switch from flora Imo.

Jacks can be used by its self (meaning the 3 part, Jack’s A, calcium nitrate and magnesium sulfate aka Epson salts) from flowe tto harvest on one scedule.

However that’s not ideal.

Unless growing in soil a silica product should be used (regardless of what nutrient you use jacks or flora)
Then we use the jacks 321 recipe 3.6/2.4/1.2
Meaning jacks/calcium nitrate /magnesium sulfate (Remeber it has to be mixed jacks/mag sulfate /cal nitrate though to avoid nutrient drop out, oh and silica should be mixed and Ph’d at least to below 7before mixing any nutrients and then PH’ing the nutrient and silica mix to 5.8 for any soil less applications).

Grabbing a bag of MKP will help as we use it as a booster Durring transition /early flower (it’s another white crystal looking nutrient)

There is a recipe for Jack’s mkp booster by green gene that I and some others have shared here.

Then in flower after the booster, so when your week 3 of flower, roughly, the ratios of Jack’s 321 has been changed by some of us to better reflect the needs in flower its something we are still sorta tweaking but my guidelines are as follows.

Flower mix 3.8/2.2/1.2.
If calcium issues try 3.7/2.5/1.1

If you want more of a boost nutrient wise the top 3 things that will help would be:
benefitcal bacteria product (fishshit/tribus)
Fulvic Acid (not humic or a fulvic/humic mix as humic will wreck havoc in hydro)
Amino acid supplement


Everybody does , its not many organic growers left ?

Organics and hydroponics don’t play especially well together. Not that it can’t be done, it’s just a major PITA (in my experience anyway). I honestly don’t find anything in Jack’s that scares me though - I inhale most of the components in Jacks in their raw mineral state every other day anyway. Only thing I deal with and don’t enjoy at all is bone ash, which interestingly enough is organic.

Plenty of organic growers using soil.

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This would be extraordinarily expensive in a large RDWC system.

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it depends on how you use it. I use Tribus in a 35ish gallon RDWC system. It takes between 17.5 and 35ml every week if I’m using it exclusively (I tend to go light around 0.5ml per gal). But I also cycle between Tribus, Recharge, and Southern AG Garden Friendly Fungicide. The Southern AG is my hydroguard equivalent.

So I end up applying, let’s say 35mL tribus every 3 weeks. A $30 bottle (100mL) would last 9 weeks. I have a liter bottle and am about a third through it since Nov 23 ish.

Anyway. That’s a detour. You’re right if I wanted to use Tribus exclusively in RDWC and used a full dose weekly, it would be $170 for 28 weeks’ of growing.

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@Graysin you need a 20 gallon fish aquarium with a cannister filter even a protein skimmer, you get the fish shit right from the ass of the fish :fish:, straight from the Rotta toota yeah , save your coins :coin:, get you a good cup full and give it right to them , ph perfect and all the fish shit your plants can eat my friend oh yeah !

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I’ve got a 10 gal aquarium going in to play with. :v: The wife wants a betta, I want the water.


I also use jacks 321 in my rdwc

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Make ur own lactate serum. Use milk rice water wash and time. I have a half gallon going now just started yesterday as I burned thru the 3 cups I made last month. Took about 4 or 5 days to make. Use 10 parts of milk to 1 part of rice water wash mix milk and rice water wash together shake cover with a napkin and rubber and it on the jar for breathing purposes leave it set til it all seperate and u have a curd and whey seperate the 2 parts keeping all the in liquid tossing the curds. Mix quarter cup to a cup of molasses to feed the microbes

Has anyone recreated the spreadsheet that GreenGene shows when discussing his modification to the 321 schedule?

is this what you are looking for

this is from his video.

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Not quite.

But I think he uses HydroBuddy, so anyone have hydrobuddy database entries for Jacks (& GH would be great)?

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That’s substantially more organized than I will ever be probably!

If you find it, let us know. I’d be curious to see a spreadsheet.

I use the jacks 321 regimen along with SOS beneficial bacteria and silicic acid. I tweak the ratio’s in flower sometimes, but the 3.6/2.4/1.2 will absolutely get you good results.
I basically copied the RDWC system that Gary from PA hydroponics makes and sells (check out his YouTube videos on it) But I used 27 gallon totes for my 3 grow sites, and the external reservoir.
And I have the 3” drain pipes ran a little different.
But it works awesome. I run a 950gph air pump, with a good air stone in each tote. I have a dc water pump that’s supposed to be 3000gph pumping water through 1”pvc pipe to the grow sites from the external reservoir. And a 1/2hp chiller plumbed into the external reservoir with an 1100gph pump, and it dumps above water level to oxygenate the water more. I’m able to be away for a week at a time, without even having an extra top-off reservoir.
One thing to note, I’ve had successful runs growing 5 plants in this 3 site system, but the plants on the ends get in each other’s way. And even with a lot of training, the 5 plants probably only produced what 3 bigger plants would have produced.