I just started digging a pond. I don't really know how many gallons it will turn out, maybe 1000 or so. I was thinking to just fill it with hose water and let the chloramine dissipate out. If it takes a few weeks that's fine, I just need to know how long it will take. I've seen "weeks" as the answer a few places but otherwise no mention. It has to dissipate eventually and usually the rate has a constant halflife. Anyone know the real answer as to how soon I can put in plants and later fish?
How long does it really take chloramine to dissipate?
- Thread starter SickBum
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As I understand it, yes chloramine would take weeks to "dissipate". However, it's broken down by sunlight (UV light, actually), so if your pond is in full sun that would shorten the time (although you need to watch the ammonia levels; chloramine breakdown will release ammonia into the water). I'd suggest getting a couple test kits to keep an eye on things so you know when everything's safe 
As I understand it, yes chloramine would take weeks to "dissipate". However, it's broken down by sunlight (UV light, actually), so if your pond is in full sun that would shorten the time (although you need to watch the ammonia levels; chloramine breakdown will release ammonia into the water). I'd suggest getting a couple test kits to keep an eye on things so you know when everything's safe
Well it is a couple ppm not much ammonia can be released, and eliminating it chemically causes far worse byproducts, and I will plant plants first anyway like I mentioned. But is there a set outer time limit to dissipate enough for fish and plants? That is what I really want. I have no test equipment and am not going to buy any.
I'd get some sodium thiosulfate crystals, they will break it down and cheaply. You'll still have the ammonia component to deal with, which the pond will deal with on its own in time. The plants will help with that also, but I'd still do the dechlor just to help move things along.
The real answer is... it depends. Chloramine won't evaporate. It will, however, break down and the products may evaporate (or dissolve in the water, e.g. ammonia). How long that takes depends on a number of factors; UV light quality and intensity, oxygenation, pH... If you don't have a test kit and don't want one, you can usually take a sample of water in to your LFS and they'll test it for you.
But isn't there some upper limit? Once the chlorine is gone the chloramine the chloramine's chlorine ought to start gassing out. I don't mind waiting, I just don't want to have to hassle with it or worry, and more than that I want to know. I usually use filter not chemical additives, but filtering a large unknown number of gallons is not practical either.
