When you practice things, you get good at them! :O
I have no idea how popular hydrocity is compared to the other levels in the genesis games, but either way, 6th is pretty damn good (better then my hydrocity time at least)
EDIT: I took a look at your time, and it is yellow
Although it varies from record to record, the color code generally goes something like this
Red: The best of the best. Takes alot of time and commitment to usually set records, though it can vary from game to game. (Popular vs Unpopular games)
Orange: You're definetly one of the better players on the site. Orange times usually mean you know what you're doing. It's usually a good goal to aim for for a game, aim for all orange times. Setting orange records can be quite a challenge
Yellow: You're good, but you could be better. You don't really know how the level works as a whole, but you've more or less found a general fast route to take. Yellow records can be a bit challenging to get your times into. For the 1337 players, yellow is about as low as they'll allow their times to go, sort of like a "this is the worst I can do"
Green: You know bits and pieces, but you haven't really formalized a route to take yet, so you sort of just try and see how fast you can get through the level. Setting green records are fairly easy and can probably done in 5 - 10 minutes if you actually try.
Blue: Your times need improvement. Either you submitted a time for a level for a game you've never played before, or you just submitted a time for a level you never bothered time attacking seriously (just played the level to beat the game)
So ya...long story short...
Red = Excellent
Orange = Great
Yellow = Good
Green = Poor
Blue = Bad