malkore said:
BillD said:
If you are only changing20% you don't need dechlor at all.
Sorry, but this is as accurate as me saying "I'm the president of the world".
Whenever chloramine is present in your tap water, you MUST neutralize it. Chlorine will outgas over several hours, but 90% of US water companies use chloramine now, because it doesn't degrade, and therefore does it's job better.
Failure to dechlor after a few 20% water changes would quickly bring chloramine levels to toxicity, and the entire tank would die off, including your bacterial colonies.
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You are making a few incorrect assumptions. When you add chlorinated water from the tap to a tank, it doesn't gas off over a few hours. It will react almost instantly with organics in the water and be gone in very short order (usually within minutes.) You can test this for your self, quite easily, as I have done. I was at the local Big Al's this week and inquired about their water change practices, and the fish room manager told me they don't use dechlor, and they change about 40% to 50%. The chlorine levels in the tap water tend to be rather high, in the 3ppm+ range.
The other statement with regard to chloramine, that it will build up over time is also untrue. In order for chloramine to function it must still be reactive. While the extra stability relative to straight chlorine prevents it from gassing off, it still must be reactive to kill bacteria. The chlorine reacts, leaving the ammonia, which is a small percentage relative to the amount of chloine. This is quickly consumed by the biofilter. Many of the choramine neutralizers, merely break the chlorine bond, and allow the filter to deal with the ammonia. The ones that lock the ammonia eventually release it to the tank. This was originally told to me by Joe Gargas, who at the time was head of R&D for Wardleys, and prior to that was a consultant, and regular contributor to FAMA amgazine. I have since tested it myself, by mixing equal portions of tank water and tap water with a chlorine level of 3+
ppm (my test kit only goes to 3ppm) Immediately, after mixing the chlorine level was .5
ppm. If it didn't react, you would expect a reading of 1.5ppm or greater. In 15 minutes there was no measureable chlorine. I suspect it was gone long before I did the second reading. Having said that, there is reason to use a dechlor, but not so much to get rid of the chlorine, as to avoid the formation of the byproducts of it's oxidation of organics, namely tri methyl halides, which are cosidered worse than the chlorine by many. At any rate, I just wished to clear up the misconceptions you seem to have about chlorine. I personally no longer use dechlor, as my fish water goes through a carbon filter that removes the chlorine, for a fraction of the cost of dechlor. I will stand by my claim that a water change of 20% does not require the addition of dechlor to be safe. If you are uncomfortable with this, by all means continue to dechloinate, it certainly will do no harm.
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