Probably a dumb idea - Chloramines

[Clawhammer]

Would it make any sense to treat water with a dechlorinater like Prime if your metro uses chloramines?

[Subrosa]

Chlorine and chloramine at the levels used to disinfect drinking water are a non-issue for plants.

[rbarata]

And if you leave a bucket of water for a day, all the chlorine is released to the air.

[Subrosa]

Originally Posted by rbarata

And if you leave a bucket of water for a day, all the chlorine is released to the air.

That's the case with free chlorine, but chloramines are more stable and do not dissipate.

[Clawhammer]

Originally Posted by rbarata

And if you leave a bucket of water for a day, all the chlorine is released to the air.

This is not true of chloramines as I understand. This is, in fact, why metros are replacing chlorine for chloramine.

Using a dechlorinator like Prime breaks chloramines into Chlorine and Ammonia and then neutralizes the chlorine.

Thinking about this topic for a few very sensitive orchid varieties.

[Roberta]

I can't think of any orchids that where chloramines would be an issue. Levels in water are low. (An issue for fish, which are exposed to relatively large volumes of water and have to draw their sustenance from it. Orchids don't that that problem. If an orchid were as wet as a fish's environment, you'd have MUCH bigger problems such as inadequate air...)

[estación seca]

For sensitive orchids the amount of minerals in the water would probably be of more concern than the chloramines.

[Ray]

My local water authority uses chloramine for 6 months, then chlorine for a couple of months before switching back. The chloramine is more stable, but the chlorine is a stronger disinfectant, so they are making sure there’s been no resistant pathogen accumulated.

There are scientific papers out there describing damage to plants by both. That said, I don’t know how those tested concentrations compare to typical municipal water supplies, so I pass my water through a carbon filter that takes both out.

[My Green Pets]

CH I'm so glad you asked before you tried it. I was thinking the same thing and tried the recommended dose of (2?) drops of Prime in each gallon of tap I used for several months. My plants began to turn yellow and sickly looking, even though I was fertilizing as normal, hadn't changed anything. Except the Prime. After a little internet research, leading me to aquarium forums and then to the Prime product website, I discovered that Prime binds up more than just chloramine. It binds up nutrients as well. My conclusion was that the Prime was sequestering my fertilizer (roughly 1/6 tsp k-lite with every watering) and the plants were looking starved. I discontinued using this product, bought some epsom salts to try to get some magnesium back into the yellow plants, and within just a few weeks everything was looking much better.
If you try it, maybe a higher level of fertilizer would be necessary to overcome the uptake by the dechlorinator. I personally will not try it again.

[Roberta]

Another thought with regard to whether there is a problem in the first place... When you water, the water is very exposed to air. Lots of surface area in the medium. And if there is any organic matter in the medium, it's also going to be a somewhat reducing environment that likely will take care of chlorine (which is an oxidizer) in very short order. (Just as for pH, if you are going to test for chlorine, do so on the runoff from the pot not on what goes in.) A very different environment than what a fish encounters (which is much more water than air). And if the dechlorinator ties up minerals, that is fine for fish (that get their nutrition from food), certainly opposite of what the plant needs. So, I'm suspecting that "dechlorinating" may be a solution looking for a problem.