STS Preparation

Breeder's Lab
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I was going through a recipe for STS preparation to try and figure out what the concentration of STS I should be shooting for in the final, applied solution. I wanted to check my math and see if my assessment of preparing STS made sense:

Part A (AgNO3 Stock Soln)

  • Fill the pyrex 2-cup measure to the 500ml line with r/o water
  • Measure .5 Grams of Silver Nitrate using the digital scale
  • Slowly pour the silver nitrate crystals in to the 500ml of r/o water while stirring
  • Stir until dissolved (15 seconds)
  • Pour the Sodium Thiosulfate solution in to a 500ml brown glass bottle and cap it tightly

Silver Nitrate’s molar mass is 169.873 g/mol, so:

((0.5 g/169.873 g/mol)/0.5 L) = 0.005887 molar AgNO3 = 5.887 millimolar AgNO3

Part B (Na2O3S2 Stock Soln)

  • Fill the pyrex 2-cup measure to the 500ml mark with r/o water
  • Measure 2.5 Grams of Sodium Thiosulfate Anhydrous OR 3.9Grams of Sodium Thiosulfate Pentahydrate
  • Add the Sodium Thiosulfate to the r/o water while stirring
  • Stir until completely dissolved (30-45 seconds)
  • Pour the Sodium Thiosulfate solution in to a 500ml brown glass bottle and cap it tightly

Sodium Thiosulfate (anhydrous) mass is 158.11 g/mol, so:
((2.5 g/158.11 g/mol)/0.5 L) = 0.03162 molar Na2O3S2 = 31.62 millimolar Na2O3S2

Clearly the formula is made to reach the silver nitrate completely with excess sodium thiosulfate. Further instructions from the post are for preparing 1 quart of solution ~946 mL, mixing 50 mL of each stock solution together and then diluting to volume. Given that the limiting reagent will be silver nitrate, assuming it reacts completely the concentration of STS in the final product will be:

(M1)(V1) = (M2)(V2); (50 mL)(5.887 millimolar) = (946 mL)(“X” mM)

X = (50)(5.887)/(946) = 0.3112 mM, or around 3 *(10^-4) M STS solution.

So does my math look solid? Is the general formula to slowly react a 5+ millimolar solution of silver nitrate with excess sodium thiosulfate and dilute to 0.3 millimolar concentration?

Edit: It’s probably actually around a 0.15 millimolar solution (or less, with loss) because each silver nitrate molecule contains one silver atom and each silver thiosulfate molecule contains two silver atoms.

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Maybe this woudl help … :sunglasses:

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same one i use. but there’s like 4 other recipes that i have found but this one i swear by

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Too much math (and I like math). I just followed Sebrings video that @George posted. I wasn’t even precise (because my scale isn’t). Worked perfectly fine.

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I litterally just did this last night with @Sebring 's recipe. It felt like darkroom all over again but thankfully in light. Everything got rinsed thoroughly in distilled water and it all was brilliantly clear when done. I guess i’ll report results within the next 4 weeks.

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I’ve followed Sebrings instructions and have had success

Cheers Johnny

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Same here!

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I asked elsewhere, but did not get a definitive answer, so I’ll ask here:

The printed instructions I recently got with an STS kit from Sebring call for DOUBLE the amount of the two ingredients compared to the video instructions. Does anyone know if this is a typo or if Sebring thought it necessary to increase the concentration?

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Maybe you just have to double the amount of part A icon_e_confused|nullxnull, this are the video instructions:

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and here’s the description on his site:

Captura

so you cannot double part B as you haven’t got enough in the kit, makes sense to use 1,6 grams instead 0,8 because you cannot do anything with the unused 0,8 so it doesn’t make sense at all … beer3|nullxnull

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The description on the site is yet another discrepancy.

What he sent was actually double both (1.6 silver nitrate and 6.32 Sodium Thiosulfate (anhydrous)).

I’m just going with the video instructions. Those are what I used originally and it worked.

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If you received that quantity then it makes sense the addendum, should be:

Part A: 1.6 gram silver nitrate stirred into 500 ml distilled water
Part B: 6.32 sodium thiosulfate stirred into 500 ml distilled water

if you just follow the video instructions it would be weaker but if it works for you just go ahead … beer3|nullxnull

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Have you used one or the other? Curious if doubling it would burn the plants.

Anyway, thanks for your replies.

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Sorry, never used it, just tried to find the logic about the note you received with the package, he wouldn’t have increased the amount of part B if it wasn’t strictly necessary, just follow those instructions if you see it doesn’t work for you … beer3|nullxnull

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Can someone help me out and correct my math.
Here are the original instructions:
-Take bottle A (30ml) and fill with 25ml RO or Distilled water
-Take bottle B (30ml) and fill with 25ml RO or Distilled water
-VERY SLOWLY Add half of each mixture into bottle C (150ml)
-Fill bottle C to bottom of bottle neck with water and add spritzer

Here are my modified instructions to make 5 batches instead of 2:
-Take bottle A (30ml) and fill with 25ml RO or Distilled water
-Take bottle B (30ml) and fill with 25ml RO or Distilled water
-VERY SLOWLY Add 5ml of each mixture into bottle C (150ml)
-Add 28ml distilled water to bottle C and add spritzer

Do my calculations seem accurate?

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You posted the same math for both?

Having made and tried STS and failed at getting viable pollen using the 0.8grams silver nitrate and 3.16g sodium theosulfate, maybe sebring wasn’t wrong by sending out the instructions calling for double the amounts in the same amount of solution :thinking:

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Amounts of sodium thiosulfate will depend on whether you have anhydrous or pentahydrate.

There is someone on another private forum who swears by 0.5g silver nitrate + 2.5g sodium thiosulfate mixing to 1:7, spraying 4x, once at the flip and once every 3 days. I just mixed some up and will try it. Remember when combining solutions ALWAYS mix silver solution into the sodium solution. If you do it backward it turns black and it needs to be clear

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The third bulletpoint holds the difference…lol…I should have shown how I got to my answer.

This is an STS kit from ShitSeeds

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Bottle A = 25ml
Bottle B = 25ml
Add half of each to 150ml bottle (12.5ml x 2).
150ml - 25ml = 125ml Distilled water to fill

Bottle A = 5ml
Bottle B = 5ml
Add 5ml of A and B, mix, add 25ml-28ml of Distilled water

Is this the same ratio? Ugh…I feel like a regard.
1A&B combined stock solution:5 Distilled water…am I close?..lol

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Okay…I think I’ve got it.
Original:
12.5ml bottle A + 12.5ml bottle B = 25ml
Bottle C is 150ml
150ml - 25ml = 125ml Distilled water

150ml Ă· 25ml = 6

So my math should be
5ml bottle A + 5ml Bottle B = 10ml
10ml Ă— 6 = 60ml Distilled water

Does this look accurate?

My mom would be so disappointed in me right now…lol

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Yeah that should be accurate for maintaining the same concentration of STS

Yay for chatgpt :joy:

Screenshot_20231113-115532
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If you only wanted to use 5ml of A and B it should be this

Screenshot_20231113-115422
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