Running 100 LED flashing at specific time intervals

Hay,
Can any one plz help me i have to run 100 LEDs that i have to run using the arduino .The arduino has only 5 v from the analoge so how could i power up the LEDs with out losing the presise flashing rate and light intensity. the flashes are milli seconds appart.
I am growing algae for CO2 metigation using LEDs as light sourse.
dont know much electronics but can tinker and read if you point me in the right direction.

the LEDs are in serise right now and i am running 10 LEDs at present

Leon

The arduino has only 5 v from the analoge

From the analogue what? With 100 LEDs you need some form of external power supply there is not enough current available from the arduino regulator or the USB.

There is lots of information you left out:- How much current does each LED take?

the LEDs are in serise right now and i am running 10 LEDs at present

Do you want to keep them like this? Do you want independent control of each LED? Do you want to dim them or just turn on / off?

each LED uses 1.5 v i need to run 100 LEDs i need it to on and off at specific intervels i mean the analog pin of the arduino plz tell me if you need any other info

i mean the analog pin of the arduino

The arduino doesn't have an analogue pin you can power anything from. The only analogue pin on the arduino is an input.

So you need to run 100 LEDs at a variable intensity with standard 20mA LEDs is this right?

each LED uses 1.5 v

So they are red?

Do you need to control each LED independently? That is be able to put any number of them on at any time?