I dechlorinate with a Sodium Thiosulphate solution that I made up, but at the moment I'm doing 50% every other day as it's a newly set up planted tank.
yeah, I thought of doing that. but i only use a conditioner for its ability to lock heavy metals. if it were available separately, i wouldn't de-chlorinate my tank at all (for 25-30% changes). this is important to use, i feel, because many of us use or tap to get our water, both hot and cold, these can be places metals leach into the system (I'm not convinced they do, in any serious way) so, for safety, i treat.
un-dechlorinated, 25-30%, changes are no threat to an established tank. after the first 12 months, i stopped using conditioner at all. i only went back when it dawned on me, as a invert and scale-less fish keeper, that i may be putting my fish at risk. by not controlling any heavy metals. that's 2 years ago now.
dont get me wrong. I'm not suggesting we all stop using it., far from it. this is a positive advert for its use.
it does mean there is no noticeable effect if, in those emergency situations, you do a 25-30% change, in.un-treated. mind you, if you are doing 50%, like standby, ATM de-chlorination is vital.
I'm unsure if the same goes for planted tanks, as i dont plant.