Cleaning deposit of hull

[rigi36]

Does anyone know how to remove stuff that looks like this?

It's a hard deposit and won't wipe off - I've tried oxalic acid, it doesn't work.

It's not a stain, just a really tough deposit.

Advice appreciated. Thanks.

[jeffstevens763@g]

Lime scale remover or brick acid ?

[willk]

A decent (2500 psi) pressure washer should sort that.

[matt h]

yep as Wilk just said. soak it first and go for it...