NL 50 - Nut flush on paired board, value bet the river?

[YKMM]

BB is 49/12/1 in 40 hands and CO is 34/0/0.17 in 40 hands. Both players are very passive. I have $20 left on the river. Value bet it or check?

Comments on the flop/turn play also appreciated.

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Hand History Converter Tool (http://poker-tools.flopturnriver.com/Hand-Converter.php) from FlopTurnRiver.com (http://www.flopturnriver.com) (Format: 2+2 Forums)

BB ($18.50)
UTG ($142.25)
MP ($52)
CO ($55.10)
Hero ($41.50)
SB ($35.60)

Preflop: Hero is Button with A/images/graemlins/heart.gif, T/images/graemlins/heart.gif.
<font color="#666666">2 folds</font>, CO calls $0.50, <font color="#CC3333">Hero raises to $2.5</font>, <font color="#666666">1 fold</font>, BB calls $2, CO calls $2.

Flop: ($7.75) K/images/graemlins/heart.gif, 4/images/graemlins/heart.gif, 7/images/graemlins/heart.gif <font color="#0000FF">(3 players)</font>
<font color="#CC3333">BB bets $2.5</font>, <font color="#CC3333">CO raises to $5</font>, Hero calls $5, BB calls $2.50.

Turn: ($22.75) 2/images/graemlins/club.gif <font color="#0000FF">(3 players)</font>
BB checks, CO checks, <font color="#CC3333">Hero bets $14</font>, BB calls $11 (All-In), CO calls $14.

River: ($61.75) 2/images/graemlins/heart.gif <font color="#0000FF">(3 players, 1 all-in)</font>
CO checks, Hero ....

[davidyang]

Raise flop, try to get it all in on the turn.

As played, push river.

[PietM]

I don't really mind the slowplay here. You're hand is not vulnerable, but if you raise here it might make villains suspicious.

Hero has $20 left on the river. Put it in there!