My problem is i have an led on pins 0 and 1 which are the tx and rx pins on an arduino mega. Even with a simple blink led on pin 13 code the leds on the tx rx pins are on very slightly. Why is this? is it because they are Tx Rx pins? is there a way to fix or stop it and bring those leds to zero.
Thank you if you can help!
I suggest you avoid using Pins 0 and 1 as they are an integral part of the Arduino RX & TX circuitry.
you'd need to do hardware modifications to stop those pins.... (lifting the USB to TTL chip from the board for example)
ohhhh okay makes sense!
Thanks alot! 
Those pins are connected via 1k resistors (or something like that) to the USB<->serial converter. Normally
they will be held high at the serial end (idle serial lines are HIGH). This means that when you do drive the
pins directly they will be protected (via the resistors), but if configured as inputs and connected to LEDs
they will light the LEDs via the small current through the 1k resitors and any other pull-up resistors in the
serial converter.
If you treat the pins as active LOW (LED+its resistor wired between pin and +5V) then you may have
fewer problems, but its often useful to keep pins 0 and 1 free so Serial debugging can be used.