How to best get yellowish-brown scum off boat?

[newenglandguy]

This is my first year with my Switzer and there is a yellowish-brown scum that covers bottom of boat below water line. What is the best method to remove this? Used a scrub brush and water, and nothing. Then tried Simple Green and that does not touch it.

Should I resort to something with elbow grease or get something going with a buffer/polisher?

Thanks

 

[NYBo]

Re: How to best get yellowish-brown scum off boat?

Try a toilet bowl cleaner with oxalic acid. If you have a galvanized trailer, be sure to rinse it off immediately.

 

[Bob_VT]

Re: How to best get yellowish-brown scum off boat?

Or Muratic acid from your hardware store..... wear the proper protective gear! We regularly acid wash fiberglass hulls with it and it works.