[Support request] Yellow leaves, fungi or bacteria?

Hello, I would like to ask…. I have two plants outdoor and I use autopods for first season. I’m experience grower but mainly inside. Plans were very nice during first monts. Than start to be little yellow and than one of them start to had spot on leaf, braun, dark and black. Second one looks 50% better but +/- same symptoms. I thought it is fungi and overwatering so I took plans out from autopods and add hydro peroxid to tank. It helps but so so. It also can be same bacteria because tube from tank is outside and there is same direct sun during the day so water can be heated. I hope that peroxide help but I’m scared to get plans back to autopods. Also I found today little mildew in blow but on better plan what does not make sense to me and I take it as since than fungi or bacteria is still inside. Im growing in soil ( Canna – Terra Professional Plus+) with hydroclay on the bottom. Thank you very much for answer. Jan