Silver Thiosulfate (STS) is your best option. Don't err on high side of concentration. In my experience, you actually get more viable pollen without 100% conversion. When i've accidentally given too high of concentration, and i had zero or limited seeds. When i didn't overdose on accident, i got 1000-1500 seeds from a 35-40gram plant -- for reference. You don't need large plants unless you are trying to open a seedbank. 1000-1500 should be enough for most people to share freely and be wasteful.
Lots of places sell STS, but they overprice it 10,000% or maybe 1,000% - not an exaggeration. For the price of one batch you'll have liters worth of STS to use in future.
STS only needs to be applied on the day you flip to 12/12, and then two more times with 5 days between each application. Day "0," 5, and 10.
Buy a size-approriate spray bottle.. if one small plant.. a 50mL is probably a bit oversized. Don't go cheap here, but they are still cheap -- the type of spray bottle that builds up pressure via pump and creates a very fine mist is what you want and not a dollar store spray bottle - avoids waste and improves absorption - no surfactant needed. An opaque, black bottle is best.
Also, STS doesn't make the plant look sickly AF. Clearly more healthy plant and probably benefits healthy seed production in some way by comparison to CS, i'd wager.
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Ingredients:
Ebay - silver nitrate - 2 usd / gram last i looked. Usually someone makes it, so this needs a little due diligence. Read reviews.
ebay - sodium thiosulfate - 7-8 usd for 113grams. Comes in proper commercial packaging.
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Following instructions at
https://www.sigmaaldrich.com/US/en/technical-documents/protocol/cell-culture-and-cell-culture-analysis/plant-tissue-culture/silver-thiosulfate
Not done, yet:
The above is just for the reaction. After you complete the instructions above, you need to futher dilute from 20mM to 2 or 3 mM. Simple algebra. either 1 part solution and 5.67 parts distilled water (3mM) or 1part solution and 9 parts dilluted solution (2mM). I'd suggest sticking to 2mM.
Use distilled water, if it wasn't mentioned. RO is even purer? So, that's fine too, i'd think. I accidentally used tap water once, and it stil worked well, but better safe than sorry.
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From these instructions you can accurately calculate how much siver nitrate to purchase and how many liters of STS solution to apply to the plant. For ~20 usd, you'll be able to make 9L of STS? Probably need 50-75mL or so for a small plant and 3 applications. something like that... you can see that it's a far better price than buying it pre-mixed and "1" use for the same price.
Other problems of pre-mix branded sts - if it comes as STS pre-mixed, it only has a 1 month shelf-life. So, there has been at least one instance where i saw a bunch of people complaining they got some branded sts that didn't work -- probably old AF. Marijuana brands are some of the most unprofessional companies you will ever deal with, lol. too ignorant to hire a chemist and listen to the chemist. The individual solutions before mixed together can last 6 months. The dry silver nitrate and sodium thiosulfate will last for decades -- just keep it dry and dark.
Don't follow uninformed instructions from forums. The proportions in this recipe (URL) ensures that you exhaust the more expensive silver nitrate ingredient. If you've taken a little bit of chemistry and can't balance the equation, it's because it is a double-replacement reaction.
Other tidbits - don't use metal... trays, spoons, whatever... also, lay something down to protect against drips or spills as this stuff will stain or corrode what it touches. Don't do this on your dinner table. It's safe, but it can superfically ruin nice things.
Get a microgram scale. They often come with little trays and scoops - get one with plastic trays and scoops, lol. Find one that is +/- .003g error. This will allow you to weight out small batches of STS. Unless you are reversing many large plants, you won't need much.
I bought 10g of silver nitrate and some sodium thiosulfate ~4 years ago, maybe 3. I've done 1-2 breeding cycles every year since. I've barely put a dent into my 10 grams. If only doing 1-2 breeding cycles a year, you may only need 5grams to last a decade of use.
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You can make your own colloidal silver with a battery, some wire and a silver coin (or any pure enough silver of some sort). But, it's not very precise as far as controlling the concentration of the output, it's not as effective at reversing a plant and you have to spray it everyday for a couple weeks. It makes the plant excessively sickly-looking, too.
If i recall you want ~50ppm.
Definitely don't buy those holistic health products claiming 500ppm of CS. These products have zero oversight and are nowhere near the concentrations they claim. Those products are for mopes that drink CS 'for their health' LOL... an RFK jr. type person that thinks swimming in raw sewage is fine.