Best method to neutralize bleach

fryman

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I use bleach to sanitize phyto culture water. After growing out a week I use the phyto as feed for copepods and also my reef tank.

After bleaching the bioreactor & culture media I "neutralize" the bleach (not sure this is the right term) either using sodium thiosulphate or UV. Is one method preferably from a chemistry perspective?

I think de-activating bleach using sodium thiosulphate creates sodium sulphate (in addition to the leftover sodium thiosulphate)? What does UV breakdown of bleach leave behind? Are any of these chemicals of concern for adding to a reef tank?

TY
 
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fryman

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I'm using bleach to sanitize the culture water.

I have used UV only to sanitize the culture water and bleach for the equipment but it's not as effective as bleaching the whole setup. Also it's more work and I'm a bit lazy.
 

Courtney Aldrich

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I use bleach to sanitize phyto culture water. After growing out a week I use the phyto as feed for copepods and also my reef tank.

After bleaching the bioreactor & culture media I "neutralize" the bleach (not sure this is the right term) either using sodium thiosulphate or UV. Is one method preferably from a chemistry perspective?

I think de-activating bleach using sodium thiosulphate creates sodium sulphate (in addition to the leftover sodium thiosulphate)? What does UV breakdown of bleach leave behind? Are any of these chemicals of concern for adding to a reef tank?

TY
One equivalent of sodium thiosulfate (Na2S2O3) quenches four equivalents of sodium hypochlorite (bleach, NaOCl) forming two equivalents of sodium bisulfate (NaHSO4). I don't believe UV will quench sodium hypochlorite (bleach).
 
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fryman

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Seachem Prime.
Seachem prime would work I expect but it's much more expensive than sodium thiosulphate. I bought 10lb and basically have a lifetime supply. I dunno if prime would be safer to dose regularly over time?

I know sodium thiosulphate is ok in the short term just concerned about it building up over time.
 
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fryman

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One equivalent of sodium thiosulfate (Na2S2O3) quenches four equivalents of sodium hypochlorite (bleach, NaOCl) forming two equivalents of sodium bisulfate (NaHSO4). I don't believe UV will quench sodium hypochlorite (bleach).
I have a small UV sterilizer I was using for culture water and I tried running it in a bucket with bleached seaawater and after a day there was no smell and no detectable chlorine using test strips. I have also tried just running the bioreactor with bleach in the sun but after several days there was still bleach smell and Cl still measured off chart on the test strip. I think if you expose bleach to sunlight it will eventually react in some way but this seems to take too long to be practical. However using a UV sterilizer the culture water is good to go in at most a day. I'm growing isochrysis in a setup prepared this way right now and it's coloring up as per usual.

I have no idea how UV neutralizes bleach but it does because I have tried it. I was hoping this was a safer way given I plan to dose some phyto to my reef tank but I don't know the chemistry.
 

Courtney Aldrich

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I have a small UV sterilizer I was using for culture water and I tried running it in a bucket with bleached seaawater and after a day there was no smell and no detectable chlorine using test strips. I have also tried just running the bioreactor with bleach in the sun but after several days there was still bleach smell and Cl still measured off chart on the test strip. I think if you expose bleach to sunlight it will eventually react in some way but this seems to take too long to be practical. However using a UV sterilizer the culture water is good to go in at most a day. I'm growing isochrysis in a setup prepared this way right now and it's coloring up as per usual.

I have no idea how UV neutralizes bleach but it does because I have tried it. I was hoping this was a safer way given I plan to dose some phyto to my reef tank but I don't know the chemistry.
One cannot argue with experimental results! At first I could not think of how UV could inactivate bleach, but after your post and reading a little, I think UV inactivates bleach forming HCl and O2. Here's a link that discusses it in more detail, see: https://www.ukessays.com/essays/biology/effect-of-uv-rays-on-pool-chlorine-biology-essay.php
 

Dkeller_nc

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I guess my question would be why you're bleaching the culture water and equipment in the first place. Most phyto/copepod culture methods I'm familiar with require oxygen saturation by means of an air pump/air stone. Unless you were growing phyto for scientific reasons were a pure culture with no bacterial contamination is absolutely required. In which case you'd be using a sterile gas filtration system and/or bottled oxygen, and you'd be running the culture in a HEPA-filtered incubator or a laminar flow hood.

A typical hobbyist setup with an air pump and an air stone would render the culture non-sterile within a minute or two of starting the air pump.
 
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One cannot argue with experimental results! At first I could not think of how UV could inactivate bleach, but after your post and reading a little, I think UV inactivates bleach forming HCl and O2. Here's a link that discusses it in more detail, see: https://www.ukessays.com/essays/biology/effect-of-uv-rays-on-pool-chlorine-biology-essay.php
TY that's helpful info. I'd think HCl would decrease pH and maybe cause precipitation? I did notice there was a ton of precipitation on my UV sleeve, although I thought it happened over time I hadn't checked it before. Maybe I should test my alkalinity to see if it has any impact
 
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fryman

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I guess my question would be why you're bleaching the culture water and equipment in the first place. Most phyto/copepod culture methods I'm familiar with require oxygen saturation by means of an air pump/air stone. Unless you were growing phyto for scientific reasons were a pure culture with no bacterial contamination is absolutely required. In which case you'd be using a sterile gas filtration system and/or bottled oxygen, and you'd be running the culture in a HEPA-filtered incubator or a laminar flow hood.

A typical hobbyist setup with an air pump and an air stone would render the culture non-sterile within a minute or two of starting the air pump.
I would not care about bacterial contamination so long as my cultures stayed the organisms I want (or at least the bulk of the culture did so). I'm just using them for feed and soon as I dump them into another tank the culture is contaminated so at that point I do not care. The problem I have is contamination taking over the culture, and eventually starving out or killing my phyto. My enemy #1 is shown in the attached image, which I believe is some type of cyanobacteria. I don't know how it gets in, but suspect either the water or salt mix. So I researched online and found some articles from aquaculture industry which stated sanitizing the culture water was standard practice even just for feed.
https://shellfish.ifas.ufl.edu/wp-content/uploads/Phytoplankton-Culture-for-Aquaculture-Feed.pdf

Also crashes seem to happen more often when I'm lax about sanitizing.

I am concerned about the air too but hoping cyanobacteria isn't airborn? I did put my air pumps inside of vacuum bags to try to keep this under control.

cyano contamination.jpg
 
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taricha

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bleach and thiosulphate is fine, and used often.
I feel your pain. Phyto cultures go off the rails easily. bleach + thiosulfate helped me a lot.
 

Dkeller_nc

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Hmm.. Well, from the standpoint of contamination, yes, cyanobacteria can be aerosolized, and it's probably likely in the air around reef tanks with some amount of cyano growth (almost all reef tanks have some amount of cyano).

From the standpoint of the "leftovers" from thiosulfate neutralization of bleach, you should be fine as long as you're using close to a stoichiometric ratio of thiosulfate to bleach. Seawater already contains a quite large amount of sulfates, and the relatively small increase from adding sodium thiosulfate to neutralize chlorine bleach shouldn't make too much difference.

There is, btw, a means of preventing contamination from an air pump that's within the reach of a hobbyist, which is filtering the air through a 0.2 um hydrophobic filter. Here's an example on amazon.

You can, btw, sterile filter your culture seawater. There are many such capsule filters of widely varying sizes in the scientific world, but they might be a bit pricey for hobbyist use. Instead, you might choose to consider camping potable water filters - these are designed with the same idea in mind, which is filtering out everything down to the size of bacteria. A pump-type might be the easiest to use (many of the camping filters are designed to use gravity from what looks like an oversized IV bag).
 

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