GeeRoGeeRo Floor Scrub Brush with Adjustable Stainless Steel Long Handle - 47" Stiff Bristle Shower Deck Brush, Multi-Surface Stiff Brush for Tile, Bathroom, Concrete, Garage, Deck

Q: Will the brush scratch acrylic tubs?

I am not sure as I have only used it on my boat floors. Seems it should not though.

Q: are the bristles on this brush really hard

This brush can be 180 degree rotated, so it is flexible while cleaning, but it's durable enough for scrubbing rough surfaces, won't break, perfect for cleaning floor

Q: I need to clean the outside of my house before painting. Is this a good brush for this?

I have no idea if this is good for scrubbing a house. It is meant to be a shower or bathroom brush and this is what I am using it for. It does that job very well.