Question

[Tim]

If I let tap water sit for 24 hours do I still have to add any chemicals or would any chlorine or whatever have disipated by then?

Thanks

[BigDaddy]

You'll still need to treat it.

Chloramine (which is used in our water treatment facilities) can take a week or longer to dissipate from aged water.  Chlorine bleeds off quickly, but chloramine doesn't, that's why they use it.

Don't forget, chloramine is part chlorine, part ammonia.  Too nasty things your fish will not take kindly to.

De-chlorinatators are cheap compared to your investment in livestock.

[artw]

I tested this fact by letting a 27 gallon sit for 2 weeks and I could still detect chlor(amine)

[Anubias]

Chloramine takes about 3 months to dissipate.