paint to water ratio

I just finished spraying the deck on a board using the Acrylic water based paint recommended in the Archives. I watered the paint down for low pressure spraying and ended up with a sloppy mess! With the paint base and tints separating out. What’s my problem ( I used a 1:1 ratio). Please help or should I just get the brush out?

I’m not sure. I’ve always used 1 to 1 with liquitex and had it work fine. Possibly you put too much paint on in one coat.