Those look aluminum. If you use bleach dilute it well & don’t leave it on too long or you’ll get oxidation if they are aluminum. Treat it similarly to an aluminum gutter. Try to do it in the shade/when it’s not in the full sun.
Wet down the grass around the pool first to prevent bleach from harming it then rinse well after.
Magic erasers are helpful also.
Be sure to use unadulterated bleach incase it gets in the pool.
If it stays stubborn/you can’t quite get it all off you can use wet & forget. It won’t hurt the pool if a little gets in it. May cause a couple bubbles. It doesn’t work immediately but rather over time.
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Welcome to TFP! For a wealth of pool care information please check out our free Pool School. If you are in need of specific help then we encourage you to Register and ask us here in the forum!