Lefthand Jacks with Peters - Hydro Experiments in 5-1X-26

Since it seems that people have interest in custom nutrient experiments, I’m going to log some experiments I’ll be doing amending a 5-1X-26 formula. In theory, this applies to several popular hydroponic formulations, including:

Peters Professional 5-11-26
Masterblend 5-11-26
Southern Ag 5-11-26 (blue razz)
And also Jacks 5-12-26 – much like the 5-11-26, but with negligible differences in P, and more significant differences in Mg (uses more epsom than the other formulas).

As a personal note, as long as I’m adding epsom, I prefer the 5-11-26 formulas so that I can provide other sources of Mg (primarily Magnesium Nitrate), and also epsom is already cheap and easily available. Note that Peters’ now lists their mix as having 6% Mg, similar to Jacks. It used to be 3.2%, so be aware of that difference and adjust accordingly.

For those interested in following along, pick your 5-1X-26 poison. I’m currently using the Southern Ag formulation, which I call blue razz, because it’s a startlingly artificial blue color. This is due to the use of copper chloride in the formulation to provide copper. I don’t prefer it because it’s more hygroscopic/clumpy than Peters, but sometimes it’s cheaper to purchase.

My Base Mix (control)

  • Southern Ag 5-11-26 (3.2% Mg)
  • Yara Calcium Nitrate 15.5-0-0
  • AgSil 16H (diluted to 1% mixture)
  • STS Super Shock (for reservoir sterility)



Amendments

I’m going to use very inexpensive amendments. The goal is to minimize costs, so I won’t be using any fancy bottles. Here’s what I’m amending:

  • Fertilome 9-58-8 (MAP/MKP)
  • Monopotassium Phosphate 0-52-34 (MKP)
  • Magnesium Nitrate
  • Epsom salt (Magnesium Sulfate)
  • Peter’s STEM micronutrients
  • Potassium Sulfate 0-0-53



First up, the 9-58-8 is a simple mix of MAP and MKP that balances N/K while boosting P. This stuff is very cheap – I think that the 1.5lb tub cost me $9 at my local garden store. My target application for this is rooting (early growth stages). Next up I have MKP, which is a standard PK booster. I will be targeting flower/bloom stage with this nutrient. STEM is a broad spectrum trace element supplement. Finally magnesium nitrate I will try as a replacement for epsom during veg (as in my coco thread).

Experiments

Bloom experiments are a little more challenging, and I’m not willing to sacrifice my grows, so these will be a little more conservative in approach. Typically, I’ll be using MKP, potassium sulfate or combinations thereof.

Veg experiments are where I’ll focus most attention. Intermittently, I plan to do more rigorous scientific experiments, possibly even to the point of killing plants due to nutrient imbalance, but still using conservative mixes for seeds I care about.

I’ll conduct nutrient “boundary tests” to determine their upper limits. This will look something like:

  • start ~10-20 seeds from my pile of randoms
  • germinate and plant into treepot with measured weight of rockwool croutons
  • amend base mix with test nutrient, while controlling EC
  • weigh plant mass and root mass after a standard period of time
  • repeat experiment to increase amendment until deficiency is caused

Qualitative experiments on plants I do not wish to destroy will also be performed. Currently, I’m starting with this mix in veg:

Standard 321 base mix, Fertilome 9-58-8 (ratio 1/10th of the hydro mix 0.3 ratio), Agsil 1% solution, 1.0EC. Fixed flood and drain cycle of once per 12 hours. For roughly 20 gallons, I used:

30g 5-11-26 blue razz
20g Calcinit
10g Epsom
3g 9-58-8 Fertilome
15mL 1% Agsil 16H
2g STS super shock

The hypothesis is that P is used more heavily during early stages for promoting root growth. @8k_feet saw some P deficiency at colder temps in his basement, possibly implying that the base mix could be amended with more P during early growth to provide a better tolerance to low temperatures, or to increase root mass.

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I know it’s been a year but I’m wondering how that fertilome worked for you? I’m trying to decide whether to get that or the monopotassium phosphate 0-52-34

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Hey @hollyho – actually I forgot about this thread… I’ve been doing a deep dive over here:

In terms of the fertilome, one thing I’d caution that I’ve learned is that MAP might not be such a good idea – though it may be a fine or even a good idea if you go deeper in learning how to apply it. The nitrogen form NH4 can have significant consequences on the root zone pH. It can be ok as an amendment, especially in veg rather than late flower… but I think you’d have to be careful to check runoff pH in coco or soil media or monitor your reservoir pH in hydro. NH4 also has a rapid uptake, so that might not be so great at certain points of the grow cycle.

With MKP, it might not be great in veg but it would probably be ok in early flower. If you are looking for a P supplement in veg, I actually think that magnesium phosphate is probably the best choice, because you can do a slight reduction in epsom and use a little bit of that in its place. Sulfur anion is way overkill in the 5-XX-26 formulas, so you can afford to sacrifice that in favor of some phosphorus. I’d have to run some numbers, but it shouldn’t take much to boost up to 60ppm, which is probably a good number through stretch. I have also had good success sacrificing sulfur in veg for nitrogen using magnesium nitrate. Since magnesium fertilizers can provide all available anion forms, I would make my substitutions there and change nothing else.

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Ok as soon as I get this journal update done, ima go check it out! I appreciate you. I’m doing jacks 321 in coco… it’s the jacks 12 not 11. Idk how that changes things. But I’ll holler at ya over there in a bit. :wink:

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