Phal white mold or fungus roots

[lassiemelove]

Hello, I am new and first of all I'd like to say:

I KNOW, I know, you get what you pay for.

I am having problems with my phals. I bought them on clearance at Lowe's because they had mealy bugs and I couldn't resist. I picked the least infected ones, took them home, cleaned them up, totally repotted....
Had a small re-occurrence a few weeks ago. Cleaned them again with diluted alcohol spray and then totally sprayed them clean a few hours later with the hose. Had to repot again because I must have overwatered and caused quite a few roots to rot.

After repotting I waited two weeks and them watered once. I just checked them with a pencil in the potting medium and was going to rewater... (It's been over a week.) More than half of them dropped the bottom-most leaf- it was yellowed but not dry... I noticed fuzzy white mold on one of them on a root I could see and pulled it out. It was fuzzy white mold on several roots.

Should I pull them all up again and clean the roots with peroxide? Where could the mold be coming from? Is there any way to clean my potting medium? I can't keep buying more. I sterilized all the pots in the dishwasher before repotting last time. Sorry this is so long!!