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Question regarding the safety of sodium thiosulfate to dechlorinate water

Hello everyone,

I haven't posted anything in months, as was waiting out winter here in Seattle and there was nothing really happening in my indoor system.  

Spring is upon us in the NW though, and I'm now back to paying more attention to my tank and hoping to plant crops soon, right now the tank has has been maturing with houseplants (which are doing AMAZING) and a grow light over the winter.

My concern that I can't find a definitive answer to is this - Is sodium thiosulfate dangerous to humans if used in system to de-chlorinate?  With rapid evaporation in my tank, and me not paying close attention since my business has been very busy, I've had to use de-chlorinator to top off my tank for the past few months.  I wasn't really thinking too much of it because such small amounts are used, but recently I started thinking I may have been flawed in my thinking.

There are a few posts about the chemical breakdown of chloramine using chemicals,  but not chlorine.  I've read one site (which now I can't find to post a ink to of course) saying that sodium thiosulfate helps the chlorine to degas quickly, and degasses itself, that seems too good to be true, lol.

My basic question that I need answered is will growing produce to consume in a tank that I've used de-chlorinator in have a chance of being harmful? 

I'm going to go set out a bucket of water to age while I wait for answers...

 

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Have you already looked it up here?

http://en.wikipedia.org/wiki/Sodium_thiosulfate

 

seems safe enough in small quantities but I wouldn't go drinking it, inhaling it or splashing it on myself or in my eyes while using it do dechlorinate the water.  It is used in medicine though.

you know, I did look it up there, and obviously didn't read far enough down...thank you!  I think I was just worrying about it a little too much, as I tend to do.  

About to go order my ziptowers now :)

TCLynx said:

Have you already looked it up here?

http://en.wikipedia.org/wiki/Sodium_thiosulfate

 

seems safe enough in small quantities but I wouldn't go drinking it, inhaling it or splashing it on myself or in my eyes while using it do dechlorinate the water.  It is used in medicine though.

Cant de-chlorinate with air over time? Or use a RO filter?

I have sen a really nice pepper hydroponics setup where an inline RO filter was used to top-off the water supply between nutrients being added as fruiting pepper plants consume a large amount of water.

http://www.youtube.com/user/Jksax914

Yes it can, and that is what I am doing again, but my question was about the safety of the sodium thiosulfate I have already added to the system and any danger of it hurting me if I consume the crops I plan to plant.

 

Also don't have space or money for an RO filter in my tiny apt.


Burton Rosenberger said:

Cant de-chlorinate with air over time? Or use a RO filter?

I have sen a really nice pepper hydroponics setup where an inline RO filter was used to top-off the water supply between nutrients being added as fruiting pepper plants consume a large amount of water.

http://www.youtube.com/user/Jksax914

Chlorine will outgass over time but chloramine won't (at least not quickly, take weeks and weeks) and more water supplies are treating with chloramine so knowing how to neutralize it can be helpful.

 

On a side note, those wanting to cycle up a new system.  If you neutralize the chlorine in chlroamine treated water, you get ammonia in your water so you need not add as much for your first dose for fishless cycling!!!!!

 

RO has costs of replacement membranes and backwashing and space, etc.  Plus I think you also loose some of the beneficial nutrients and elements that are usually in tap water.

Also, the sodium ions in the water can compete for potassium in the plant's nutrient uptake process.  This may or may not be a good thing depending on your situation.  In most cases in aquaponics, probably a good thing since most are already deficient.
I'm still trying to figure out the chloramine thing too.  I'm getting close to cycling my system, so I have to get the choramine out.  I ask this question not totally understanding the chemistry of the product.  Is there residual sodium?  Will that build up over time and harm the plants?
Check the label for the dechlorine/chloramine water conditioner; it will say for aquarium use only, not for food fish. Read the MSDS for sodium thiosulphate; not reassuring. To deal with the chloramine, you can set the water in the sunlight and aerate for a week or slowly filter through clean activated charcoal. Are you able to do rain catchment?
A carbon filter is probably your best bet for dealing with chloramine since it is supposed to take weeks (plural) to really get rid of by aeration and sun.  Sylvia sells the carbon filters for use on a garden hose.
The clean carbon and slow (a pint per minute) are both important for chloramine. UV lamps would break the bond = you'd need to deal with the chlorine and the ammonia. Since you haven't cycled yet, vitamin C is an option. 4ppm (.08 gm/5 gallon of water). The ascorbic acid would be more difficult to use for your top up water after cycling, because it is anti-bacterial/anti-microbial.

The chloramine is my biggest obstacle to getting my system started.  The vitamin C sounds like a good option to get going.  Its in the plans to eventually put gutters on the greenhouse, but that's down the road.  I'm way over budget and time.  Is a carbon filter easy to build?  Would the one on the end of the hose work?  I have a 900 gallon system, so it's not like just filling up an aquarium.  Thanks for all the input.

 

I expect this is a good option for starting up a new system

Hose filter

And probably also a good option for topping it up too.

 

Unless you water is way hard and then it might be worth adding an RO filter to remove some of the calcium carbonate and make system pH and nutrients a little more controllable.

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