Bone Headed Mistake

[rstar]

In my infinite stupidity today i had my light fixture upside down on the rim of my tank to clean the bulbs and i accidently dropped one end of the fixture into the water. Needless to say i think i shorted out one of the ballasts on my tek 4 bulb fixture. Are they easy to get at and replace? Is there something i can check to see if it is infact the ballast? When i turn the switch on for the two bulbs that wont light the switch turns green so it is getting power.