Mold in yeast/sugar C02 producing container

its in a plastic five gallon bucket frome home depot. it turned the plastic below the water level dark! it had mold floating on top and smellls strongly of mold. i rinsed it out with hot water.scrubbed it hard with pure bleach. its still dark and still smells like mold. can it really penetrate plastic or something? i mean i scrubbed it with an abrasive scrub pad with pure bleach how can the thing still smell? i still want to use it still. will the mold come back quick with yeast water and sugar?

Something is wrong with the container so I'd toss it. I don't want anything that lives through a bleach douce
anywhere near my plants.

I use a one-gallon plastic jug as my CO2 generator. Every 4 days I rinse out the jug real good before I re-mix
the ingredients. I use 2 cups sugar and 1 1/2 tbsps. of yeast and half fill the jug with water as hot as I can get it.
CO2 is heavier than air so it is a good idea to hang the jug up near the ceiling fan and let the fan blow the carbon dioxide
down around the plants. I figure the CO2 generator adds 10% or so to my yield.

BigSteve.