Shock Treatment - Or how to kill Chloramines

[Scott_sg]

As part of my ongoing obsession now with water chemistry, here is the way to get rid of chloramines. I asked my cousin who owns a public swimming pool in Australia about them, he laughed and told me where to look. Apparently the swimming pool people can't stand chloramines as they irritate eyes and skin worse than free chlorine.

*** Don't do this to a tank with fish, it is a water treatment for people who want to prepare water in advance ***

So this is probably ideal for anyone with a fishroom (fish corridor) or serious about breeding fish.

The idea is really simple, just add lots of extra chlorine, the swimming pool people call it shock treatment or super chlorination.

The chemistry is that when chlorine is added to water it forms hypochlorous acid HOCl which becomes H+ and OCl-, with ammonia around it becomes chloramine (the one we dont like) NH2Cl - but in the presence of more chlorine oxidation continues to form dichloramine NHCl2 and then finally trichloramine NCl3.

The trichloramine is unstable and breaks down to Nitrogen and Chlorine gas at what they call the chlorination breakpoint.

This will also work on other organics that might also be present in the water.

So for everyday purposes it is as simple as having water storage tubs, add lots of chlorine, lots of aeration and then let it sit for at least a few days for the chlorine and nitrogen to dissipate.

So now a great use for those chlorine test kits to check when your water is ready.

The only catch is that chlorine must be in excess or you will just make more chloramines. It takes 7.6 parts of chlorine to oxidise 1 part of ammonia, so at a minimum you would need 10x more chlorine than your combined chlorine levels.

An easy fix for people like me obsessed with water. On the net look up pool shock treatment, super chlorination. There is tons of stuff on getting rid of chloramines.

Use at your own risk.

Scott.

[whuntley]

Caution, Scott.

I found out the hard way that chlorine does not dissipate by just standing. It need aeration or other vigorous circulation to do the job properly.

In a clean more-or-less covered (not sealed) container, it hangs around indefinitely. Circulating air over the surface helps, but there is nothing as effective as vigorous air, bubbling through it and carrying it away.

Wright

PS Many of my little tidbits like this one represent some dead killies because I did something stupid. On some small fraction of those, I managed to learn something.