Hydrogen Peroxide for Dechlorination

[Jay Mottz]

Hello all, 

Like many of us, I add water to my system from a municipal water source which contains about 1 mg/L of free chlorine. We first process the water in a 55 gallon drum by adding Sodium Thiosulfate, then circulate the water for a couple of days, or until the free chlorine mesures 0 mg/L with a DPD test. 

I recently read an article regarding the use of Hydrogen Peroxide to dechlorinate wastewater effluent before it's discharged.

I'm wondering if any of you have tried this method for dechlorination?

Do you feel this would have an adverse effect on the nitrification bacterial colonies?   

Thanks for your feedback. 

Jay

[Vlad Jovanovic]

Well if it's only chlorine in your Muni water, you could always just let it sit out with the lid off for a couple of days. Or get fancy and put in an air stone or two.

Are you sure you didn't mean chloromine instead of chlorine? Sodium Thiosulfate might be a bit 'drastic' for just chlorine no?

[Jay Mottz]

Yes it's chlorine. I use Thiosulfate because I have it in bulk, I agree that its use is overkill, as well as creating issues with DO loss... This is why I'm looking for an alternative.   So aeration will work as well as any chemical? 

Vlad Jovanovic said:

Well if it's only chlorine in your Muni water, you could always just let it sit out with the lid off for a couple of days. Or get fancy and put in an air stone or two.

Are you sure you didn't mean chloromine instead of chlorine? Sodium Thiosulfate might be a bit 'drastic' for just chlorine no?

[Vlad Jovanovic]

Yeah, my understanding is that chlorine will just off-gas when aerated (or left to sit out long enough even w/o the added aeration, just takes longer that way). I'm on well water myself...but that seems to be the general consensus among people here...  

Hydrogen peroxide does have anti-microbial properties, and may or may not do funky stuff like oxidize your plant available Iron(II) into bio-UNavailable Iron(III)  (depending on how you go about it and a host of circumstances of course). If you do go that route, I'd suggest using the solid form of hydrogen peroxide, Sodium Percarbonate. It keeps much, much longer than the liquid hydrogen peroxide, and you can mix up batches of your desired strength. I've also found a million other uses for it around the house/shop. Real handy stuff to have around.

But really, try just aerating your water for 24-48 hours, then test it...see for yourself. (But this is what many people do).

[Eric Warwick]

If you do, be careful! I burned myself today cleaning my hydroponic systems with H2O2.

[Jonathan Kadish NYC AA Chair]

I was using Thiosulfate but now I use an RV Hose water filter. I don't have a chlorine test kit, nor do I have the space to let water sit, but hey, my fish aren't complaining. I will use this filter for a couple of years or about 2000 gallons and then replace it. I just feels right to take chemicals out rather than add them.

[Izzy]

I would not recommend using sodium thiosulfate because you could inadvertently create a toxicity in your system for some of the biota.

The use of H2O2 seems quick and easy, but simply aerating the water for a short while, as others have stated, would yield the same result.  More importantly, depending on your source of water, it may not be necessary to dechlorinate your water whatsoever.

Remember, plants need chlorine too.  It's essential for their growth at the appropriate quantities.  Food for thought.  :-)