I know next nothing about this guy, but have seen him over-active, betting and calling big bets in the lead up hands to me entering the table, and assume by his stack he's hitting a lot of hands and drawing people in who think he's bluffing.

Any problems with this until the turn? Do I check or push when a flush completes with such a calling machine here?

Poker Room skin
No Limit Holdem Ring game
Blinds: $0.05/$0.10
5 players
Converter

Stack sizes:
UTG: $7.65
CO: $8.80
Button: $29.80
Hero: $9.90
BB: $25.00

Pre-flop: (5 players) Hero is SB with
UTG calls, CO folds, Button calls, Hero raises to $0.4, BB calls, UTG folds, Button calls.

Flop: ($1.3, 3 players)
Hero bets $1, BB folds, Button calls.

Turn: ($3.3, 2 players)
Hero bets $3.5, Button calls.

River: ($10.3, 2 players)
[color=#cc0000]Hero ???