Would love to hear your expertise. Quick summary: I got a stinky res and want it to be not so stinky.

I'm using Canna Coco nutes and Plagrons Calmag and Silic Rock.
It's an Autopot reservoir with an added wavemaker to keep the water moving every hour. It's a 47L/12.4gal res I fill up to 10L/2.6gal. The res smells like wet old laundry very quickly, most likely cause of the room temp never dropping below 20C/68F. Water turns murky but no film on top. It doesnt really thicken. Just gets a stink.

I've been suggested and am considering H2O2 but dont know if it would fix the stink or not. Did read it will mess up Ph and kill everything in sight.