you might want to raise the turn there - At least the Villain (not even knowing his cards) is very interested in this pot - If you put him on best possible hand it is top set. If he has top set and you have NUT flush, he has 10 outs to make boat (3K's, 3 5's, 3 3's and 1 Q for quads) - that means you are roughly 4:1 favorite (he has 10 outs, only river left is ABOUT 10x2 for 20% to hit paired board - just using rough 4x2 rule) - Basically its like you taking AA's against KK's for all the money preflop - You would do that everytime right? I think you played it perfect - If you bet at the nut flop 20%, that is a good amount of mixing up - I like the slow play here - You are way ahead, Villain is aggro - this is a good spot for you....Just got unlucky -

Also, that is a really good idea about the $20 challenge - Did you have a goal in mind? Or did you just want to see what you could get it up to with no thought of cashing it? Maybe next time say if you get it to $500 cash it and do it again...? I think that is excellent practice though - and you got up there in 4 days? WOW _ you are definitely doing something right -