powerhose a 3d background?????

[hoopy11]

hi.new here,any help appreciated..i have a 140l tank.im going to clean it out this weekend,i have a 3d background but it seems to have got very dirty,its really hard to clean as its like black grinded in to it..dont feel safe using bleech,just asking has anyone ever powerhosed one before or ideas for getting it back to new again would be great,thanks