Fungus like all life require a few things, air, moisture, warmth.
Hmm don't be disheartened brother, 90% of growing problems come from environmental conditions. You may want to consider watching Bruce bugbees videos you can find on YouTube these are lecture grade and there is one specifically covers the 9 cardinal rules of plant growth.
Stagnation is your enemy.
Best solution to fungus imo is UV that's going to set you back a few 100 though. (Solacure)
Going forward look to have your grow environment with a negative pressure. Keep the humidity below 50rh.
There is no solution that won't cost money and time. Msg me if you would like help with information to get your environment set up I'd be glad to help.