Flop trips in unraised pot, connected board, help me with turn bet!

1/2 NL Harrahs

I have a tight aggressive image at the table. I have been opening up between $15-$20 and making lots of continuation bets. Have only showed down premium hands so far. I have $300, MP2 has $200, MP3 has $50. MP2 is aggressive with his draws and will stick around with them or overbet them.

I call UTG+1 with 77, 4 calls behind me.

Pot $10, Flop comes
7 [img]/images/graemlins/spade.gif[/img]8 [img]/images/graemlins/diamond.gif[/img]5 [img]/images/graemlins/club.gif[/img]

I bet $10, MP2 calls, MP3 calls

Pot $40, Turn comes
J [img]/images/graemlins/spade.gif[/img]

I bet $50, MP2 gets pissed off thinks for a while and mucks his hand, MP3 folds. MP2 says "Big bet huh, I can't call that", I say "Not gonna make your draw this time", he says sarcastically, "yeah, youre such a great poker player you know that".

I am thinking my $50 turn bet was a little too much, How does $30 look here?