Angry Discus when WC

[wuvarien]

Wondering how many others experience this,

My Discus hate water changes. I've tried all times during the day and get the same results, they go darker huddled up in the corner and attack the syphon when I get close.

[jwcarlson]

Mine don't have any issues other than getting a bit spooked sometimes, but for the majority of the draining they are just behaving normally. Once it starts to fill up they start eating as soon as they are upright again. I feed beefheart during refill.
For reference I'm doing about 90% change every night, only about an inch of water left, so they're laying on their sides. Mine are "used to it" by now. Been almost a year.