mega 2560 and 30 leds

I'm in the planning stages still for this project.

I want to control 15-20 rows of 2 LEDs with my Arduino. Each row I want to have turn on in sequence. I don't need them to dim just on for 45secs and then off again.

according to the specs each output has a max of 40ma. With both LEDs lit they will draw 40ma per output.

My question is, should I risk it and go directly into my Arduino or should I use relays for each output? The farthest run from the Arduino will be 25ft. My thinking was to use relays but I wanted to get some input.

My question is, should I risk it and go directly into my Arduino or should I use relays for each output? The farthest run from the Arduino will be 25ft. My thinking was to use relays but I wanted to get some input.

No, use an external power supply like an old cell phone charger. One that outputs about 5 volts at around 1A. And you can also use NPN transistors to supply this voltage to the LEDs (needs resistors too). If you want to save pins on the arduino, then you can also use shift registers as seen HERE. (this one is retired model, but just to give you an idea of how it works.)

The LEDs are to come on in pairs? Unless they are Red, you will need a higher voltage to drive them in series, or limit the current to each one to ~10mA each if they are wired in parallel to an output pin. I would use six TPIC6B595s to drive the LEDs. High voltage capable, high current capable. Have an array of 6 bytes representing the up to 48 outputs, use SPI.transfer (or shiftOut) to send the data from the array when it needs to be updated.

Yes they are going to come on in pairs, and they are white LEDs. I've played with them and will light up at 3v even though the specs say 3.2v. I'm lighting up a small hallway. They will be mounted in the drop ceiling and come on when the door to the room is opened and the motion sensor is triggered.

will light up at 3v even though the specs say 3.2v.

No the specs do not say they will light up at 3.2V, it says that when the quoted current is reached then 3.2V will be dropped across the LED.