Thank you fellow programers for stopping by to read my post.
As I may have mentioned before I have a vision for computerising my fish tank. Some of these items will run using real time clock but some will use the millis() command. however i have read that after 50 days or so millis() overflows. Is it possible to reset millis() before overflow occurs ie on a daily basis?
You might be misunderstanding what "overflow" means. "Resetting" (presumably making it start from 0 again) is exactly the same thing as what happens when it overflows, so however you would handle timing during the reset is exactly how you handle it to prevent reset from being a problem.
In other words, use subtraction.
if( millis() - beginningOfInterval > intervalLength )
beginningOfInterval += intervalLength;
// whatever you want to do.
As long as the interval you're timing is less than the overflow period (~50 days), you can forget about overflow. It won't be a problem.
And honestly, anything you're timing on a 2 month interval should be using the RTC anyway.