1st time using the XL AutoPot need guidance

I will be switching my auto pot on soon and i will be using Jacks 321 w/ Epsom salt & silica but need some guidance.

  1. What is the proper way to mix jacks nutes?

  2. How do i keep the PPM and PH from drifting in my 12gal reservoir?

  3. I started this grow with ILGM Nutes package but i want to run Jacks 321 when i switch to the auto pot. Is this safe?

My setup is grow tent, XL autopot 12gal reservoir, 5gal fabric pot, coco perlite w/ 2in layer of PH neutral clay pebbles in the bottom of the pot.

Runtz Auto
76° F
45° Humidity


Per gallon-3 ml of silica and stir, then 3.6 grams of part A and stir until completely dissolved, 1.2 grams of epson and stir until dissolved then 2.4 grams of part B and stir until dissolved. PH to 5.8-6.0. This was the recipe I used for 2.5 years then over the last year I’ve gone to silica, 4 grams of part A and 2 grams of part B and no Epsom salts. Part A has enough magnesium and sulfur to omit the Epsom IMO :love_you_gesture:


I don’t usually get much drift at all using the same set up/nutes… I mix in a 5gallon bucket with an aquarium power head pump to do the stirring… silica always 1st and I usually let that mix a bit longer than the others. A bit of ph swing can be a good thing sometimes

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I run autopots with 3 gallon fabric bags, no autos. My mix for a 5 gallon bucket is: 2 ml silica, 18 grams of Part A and use a wavemaker to agitate. 12 grams Part B and 6 grams Epsom. PH to 6.0.

I’ve been running this combo for 3 years and love it. No flushing, run water the last two weeks before harvest. Plants stay green and vibrant all the way to harvest.


I feel like I was using way too much silica… I’ll have to check my recipe. No current grow, headed out of town for a month or 2…

After following your mixing process what is the typical PPM ? I got 1720 for PPM in my 5 gal bucket i mix the nutes in. Is that normal for the autopot reservoir?

I used a 5 gal bucket to mix and my water temp is 90° to help dissolve the nutes. Could the temp play a roll in the PH and PPM?
PPM: 1720
PH: 60

So i diluted the mix with PH’d tap water.
My 5gal mix is:
PPM: 1090-1100
PH: 6.0
I think this is good to go now. 1790 was too high in my mind and i was afraid of nute lock.

I guess my question really should be, is it okay to dilute until i reach the PPM i want or should i have started all over and adjusted the measurements slightly below what i understood to be your recipe for success?

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1790 seems too high… what water are you using and what is the ppm of it before you add anything? Also if you’re using tap do you let it sit or go right to the mix with it?

I used warm tap water. I didn’t check the PPM before i made the mix but usually my tap water is around 160PPM before i add anything to it.

It was roughly 30 minutes from the time i collected the tap water to when i start mixing everything.

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That’s a good number for tap. If your on any kind of city water your best to let it sit to gas off the chlorine that they add.
For your total Ppm’s the tap water counts in your final mix

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My base water is 130 ppm, mixed Jack’s in and I get between 950 and 1,000 ppm. This is ideal.

You can also add a teaspoon of peroxide to a bucket of water to degas it.


Here is an updated picture after LST attempt and switching on the Autopot.

Dumb question alert:
How does one check the RO PH & PPM when the Autopot is turned on?

On my last (1st timer) grow i top water feed the plants whole lifecycle so learned how to collect the RO at each feeding to check my Output ph & ppm.

Before (bottom) & After (top)

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With Jack’s don’t bother. Maintain your input TDS & PH and you’ll be fine.


No need to worry about run off unless you’re having big issues… you can check the ph right in the tray and the rez. My jacks mix stays really stabil but I generally mix 3gl at a time and rarely have more than 5-6 gallons in the rez at a time


I’m pleased with the results so far.:blush:

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First using a net to support my plant. I like it. I have to add another layer to it for when she gets bigger.

Set to watching if you don’t mind a tagalong, thinking on autopots myself.

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Using your mix how long does 5 gallons last in flower typically ?
Im starting 4 / 3 gal fabric system in a few weeks.

Peak demand will require about a gallon a day per plant. I mix in buckets (Homers) for my reservoir. With Jack’s I don’t need to flush either.

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