I'm half suprised that that gave you a number in the first place! Wow, learn something new every day!
Ok, lets take a look. At this point, we have no idea if the code I provided for you is actually flawed or not. That is based on Server time and offset, not client time. So, use what Len Whistler provided to change you're offset to a valid EST timezone. Next, modify the code I provided to this:
That will also show you what the current time is. Compare the Remaining to the Current to see if its actually functional or not.
$iTimeTo = strtotime("00:00 tomorrow");
$iDiffTime = $iTimeTo - time();
printf("Current Time: %s\n", date('H:i:s'));
printf("Remaining: %s\n", date('H:i:s', $iDiffTime));