Sodium Thiosulfate....read this!

This might be a little long , but I wanted to post the ordeal I just went through over the last week or so. I was having a problem with a crashing Ph, and when I mean crashing.....from 7.0 after a water change to 5.0 and possibly below almost overnight. Some of you may remember in a thread I posted a few days ago I asked about meds accumulating on the bio-wheel ( white spots ) and having plants soften your water and drop your Ph low, etc. Well I was carring out the prescribed water changes on both my tanks like some suggested on here. I hadn't picked up the coral or tried any dolomite ( plentiful in the Niagara River gorge ) that is found around here to harden the water up and go the natural route yet either. SOMETHING just didnt add up as to why it would drop SO much SO fast.....
I spoke to my old man who is a chemist and a chemical plant manager for 34 years and knows more about that stuff than I care to listen to, but had some wonderful insight. We turned to what I use as a De-chlorinator. I use Jungle ACE , and Kordon NOVAQUA as a conditioner...which looked to me like a Stress Coat kind of product. I remembered reading on here that a lot of the De-chlor/chloramine products use Sodium Thiosulfate to do what they do. We consulted his Merck Index , the chemists "bible" according to my old man and I found exactly what was causing the problem. I was adding TOO MUCH of this product which was causing a reaction with the C02 given off by the plants and the H20 which as an end result was giving me Sulphur Dioxide, Carbonic Acid, HCl among other things...which I don't have time to post right now or remember ( if interest in this post rises , I will gladly post more on it later ) Every syptom I had was due to my putting too much of this in the tank, I'm guessing that both products I used contained it since they both De-chlorinate. Any opinions or questions , PLEASE write back or if anyone has any other ideas , I would love to hear what some of you chemistry guru's have to say!!! Thanks , sorry for the long post.

steviem

That's the thing...I was putting in wayyy to much thinking I was following the directions right. On the back of the bottles they list to put in 5ml / 10 gallons of water, or 1 capful per 10 gal. I mistinterpreted and added the amount based on what size tank I had instead of how much water I was changing. I normally would add 2 capfuls ( keep in mind I had the equation backwards ) for my 5 gallon water change, thinking it was for the total amount of the tank contents. At the same ratio I was adding 2 capfuls of the Novaqua as well. So in essense the tank was getting 4 shots per water change. What I should be adding for a 5 gallon water change is 1/2 a capful or 2.5mL of one of those products, period. UNfortuntately I was a victim of marketing.
It was suggested to me that changes of less volume more often were more beneficial and would keep the Ph swings less severe and on a whole would help maintain a steady Ph. So that is what I did, but this was compounding the problem beacause I was OD'ing the tank on this stuff and just adding fuel to the re-actions that were taking place.
I am definitely a beginner at fishkeeping and after losing a couple fish this week, learned a HUGE lesson. I just wanted to point out potential danger...I never really saw anyone ask questions about what would happen if you put too much De-Chlor in there, and they even state onthe back of the Jungle ACE bottle that it can be Safely used up to 3 times the amount recommended on the bottle....although by ratio I definitely topped that. It also disturbed me that I could not find an ingredient listing on either of the bottles, just a number to call with questions. I'm not trying to say that these products are solely responsible either. For a certain chemical reaction to take place there has to be the proper conditions, which appearently my tank had!! This might not be the case for everyone....just a little "experience" I went through and I thought might open up some discussion onthe subject. Thanks for reading...

steve

I just grabbed pops' Merck Index as I thought I would throw down some info from the Sodium Thiosulfate listing that might make things clearer. Keep in mind that I can't do subscripts for reactions either, so bear with me.

( Na S2 O3 ) Sodium Thiosulfate. p.1243 ; 8542

Use : To remove chlorine from solutions according to the equation Na S2 O3 + 8Cl + 5 H20 > ( yields) 2NaHS04 + 8HCl and Na2S203 + 2HCl > (yields) 2NaCl + H2O + S + S02.

OK...great, what does that mean to the layperson??

When Sodium Thiosulfate reacts with Chlorine, by products from the reaction are ( HCl ) Hydrogen Chloride which then reacts with water to form Hydrochloric Acid. Also , other by-products from the reaction between Sodium Thiosulfate and Chlorine are NaCl ( Sodium Chloride , Salt ) Sulfur ( S ) , Sulfur Dioxide ( SO2 ) and additional Water ( H20 ) . The remaining by-product of Sulfur Dioxide ( SO2 ) will then react with Water ( H20) to form H2SO3 or Sufurous Acid which could probably be the source of the slight acidity ( 5.0 ) of my water and the Sulfur smell I had coming from my tanks.

Keep in mind this is a reaction that takes place only if certain elements are in place in the right concentration...if you add Sodium Thio to water if there is little or no Chlorine...you don't have the reaction or you have the possibility a different reaction taking place or it will only take place until the available chlorine is used. This is why I hated chemistry in High School and College!! Too many possibilities!

steve