My carpet covered pool deck has moss growing on it. I can not figure out why. Under the deck is aluminum. Previous pool was up for about 15 years, and never sprouted, same type decking , nylon carpet over aluminum panels

1. Pool is in the sun 100% of the day.
2. It sprouts after it rains and it dies off after a sunny day.
3. If it is warm & humid overcast out, it will sprout.

I have tried a bleach solution, did not work.
I have power washed the entire deck, and it worked for a couple of weeks.

Any suggestions on how to get rid of it?