the higher the temp the quicker the chlorine loss
Chlorine typically takes about 24 to 48 hours to dissipate in a swimming pool, depending on factors such as sunlight, temperature, and water circulation.
If the chlorine level is correctly maintained this should not be a problem.
swimming pool
To disinfect it.
Chlorine is a gas at room temperature. It can be purchased in cylinders for the swimming pool industry. From there it depends on what you call expensive. You can't just go down to the local store and buy it. Solid chlorine would need to be stored at below -34oC . This would be expensive.
Chlorine is added to swimming pool water to disinfect it.
It is necessary because the chlorine kills all of the germs that enter the swimming pool.
If your talking about Swimming pool its because your pool has chlorine in it and chlorine kills fish :(
chlorine
The swimming pool at the Landmark Hotel in London is 15-metres. It's a heated and chlorine-free swimming pool. One can enjoy swimming in this pool without worrying about the side effects of chlorine, especially if one is pregnant.
The liquid chlorine formula used for swimming pool maintenance is typically sodium hypochlorite (NaClO).
Probably the chlorine. I doubt if chlorine is healthy for frogs.