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  Topic Review (Newest First)
01-02-2013 09:49 PM
m00se Yea it's a head scratcher innit? LOL.... I've been using the 160g/500ml and dosing at about 1 drop per gallon, but I must admit I tend to be pretty liberal with it. When I do a water change and I change out 20 gallons I will use about 10ml of this mix. Do I need to? I don't think so. The sniff test on my gallon jugs of top off water suggests that the chlorine is gone at 1 drop per, but I err on safety. At $3.25 a lb I'm not worried.

As far as ODing this stuff, I think it's pretty universally thought that it's difficult to do. Surplus just oxidizes out of solution and leaves salt.

HTH and Greetings back to ya!
01-02-2013 08:16 PM
jart Hey m00se,

I have some of the bulk crystals of sodium thiosulfate as well. I was doing a google search regarding how to dilute it and I happened upon the skeptical aquarist's website. I actually made a post there stating that 1g in 1L does not provide a 1% solution (which kuro pointed out). Still confused, I stumbled upon your post.

Following the directions outlined on the Kensfish website (and also the directions provided by GeToChKn), you will prepare a solution of 13% sodium thiosulfate. Quite different from the 32% that you obtained from the API website.

I have 3 possible thoughts regarding this discrepancy:

1) sodium thiosulfate is relatively safe, so the potential for error is small... better to overdose than underdose (I don't quite buy this one... why add extra chemicals if not needed)
2) the numbers may differ depending on what hydrous form of Na2S2O3 you are mixing (I'll gladly defer to kuro here )
3) the amount that should be added to treat x gallons of water will be quite different depending on what concentration you are using. So obviously, you would need 2-3 times as much 13% solution to treat 10 gallons of water (compared to the 32% solution).

So given this, I'll ask... how much of the 32% are you adding (per volume)?

For the record, I have been mixing a 13% solution and have been adding 5 mL per 20 gallons of water changed. Fish are fine after more than a year of this.

Greetings of the season.
05-16-2012 04:16 PM
kuro Not to sure but EDTA is chelating agent which is used to bind metals so in the cause of water conditioner it probably used to bind heavy metal from tap water to make it harmless. So i don't think you need it unless you worry about copper or other metals that might leech out from your pipes.
05-15-2012 11:53 PM
m00se Ok, this makes sense! Thank you very much, kuro. Now, any idea why they put EDTA in their product? My guess is they use it as a preservative. They put 9.8% of it in there.

Thanks again!
05-15-2012 05:04 PM
kuro LOL sorry i just woke up too ignore "they". Concentration percentage of mass-volume is Weight divide by Volume x100% so 1g/100ml(H2O) *100% is 1% solution like 1 gram of sucrose divide by 100ml of water time 100% is a 1% sucrose solution or in your case 1% sodium thiosulfate is (1g Na2S2O3/100ml H20*100%). You stat you want 32% of sodium thiosulfate which is (32g/100ml *100%). You stat you want to make 1/2 liter which is 500 ml and you want to get the mass of sodium thiosulfate so to do that we did (32g Na2S2O3/100ml *500ml)=160g Na2S2O3. Now (160g/500ml *100%) give us 32%. To make extremely it precise add 160g first then fill it up to 500ml mark with distill water. If there any confusion just ask.
05-15-2012 04:02 PM
m00se kuro - who is "they"? Please educate me as if I were 5 yrs old, so that I can understand this!

Thank you in advance.
05-15-2012 01:54 PM
kuro When they going by volume it usually out of 100ml, so 1g over 1000ml will be 0.1% not 1%. So to make a 32% solution it would be 32g/100ml so to make 1 liter you need 320g. To make 1/2 Liter you need 160g not 16g.
05-15-2012 03:53 AM
m00se Yep, those are the exact directions Ken's Fish has on their website. It's also why I don't trust the Skeptical Aquarist's 1g/L formula.

If there are approximately 8 half liters in a gallon, then 1/8 of 500g would be 62.5 grams...

My head hurts....

Trouble is, there's VERY little info I have been able to find online with any solid numbers.

How do you get 32% of this solution is my question I guess...
05-15-2012 03:37 AM
GeToChKn I found this

" Sodium Thiosulfate as Pond/Aquarium Dechlorinator

Chloramine vs. Chlorine...

The following stock solution of Sodium Thiosulfate does not treat for Chloramine, only Chlorine. Chloramine is a chemical compound composed of chlorine and ammonia and more and more utilities are converting to its use. Check with your municipal water company to learn which chemical they are using. If Chloramine is the disinfectant, please research other knowledgeable sources to learn your best solution for water treatment.

To begin...

Obtain a clean one gallon jug. A photography supply store will likely have good brown jugs. They are used to store darkroom chemicals. Dissolve the 500 grams of Sodium Thiosulfate in a large pitcher of lukewarm tap water. Stir until all the crystals are dissolved. Then transfer the solution with a funnel to the gallon jug. Top off the jug to make a full gallon of stock solution.

* Add 2 drops of the stock solution per 1 gallon of the water to be treated.
* One gallon can treat 37,850 gallons or more. Over-dosage is virtually impossible."
05-15-2012 03:23 AM
Anyone made their own Na2S2O35H2O dechlor? Need numbers here...

I bought a pound of sodium thiosulfate to make some dechlor. Skeptical Aquarist article says that 1g in 1L of distilled water makes a 1% solution. That doesn't ring quite true to me, but I'm terrible with conversions. The MSDS for API Tap Water Conditioner tells us that their solution is 32% Na2S2O35H2O....

Soo.....anyone have their experience to share? I made up 1/2 liter of it and added 16g Na2S2O35H2O to it. Did I replicate Tap Water Conditioner correctly?

Also, API adds EDTA to it. I assume that's as a preservative. Should I sorry about that at all?

Thanks in advance!


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