Right on! You remind me of myself
You don't need many moon lights (blue). A couple of watts worth of them will give a pretty good illumination at night. I think I have 1.5 watts worth of them on a 50 gallon tank and its plenty IMO.
I would focus mostly on COOL WHITE (6500K) LEDs. I would maybe do 1/3 warm white, and 2/3 cool white. My understanding is that plants do best with cool white(~6500K), any other colors you add are really just for aesthetics.
Make sure whatever LED strips you get that you add up the wattage to figure out how much you need.
I have my warm LEDs fade on in the morning (to simulate sunrise) and then fade out around noon time, with the Warm white LEDs fading in around 8 am, then being on %100 during midday. So the tank is a yellowish white in the morning and fades to blueish white at midday, then fades yellowish white in the evening, which is pretty close to sunlight. Not hard to do with an Arduino, and I think its a really cool effect.
I could go on for paragraphs telling about how I programmed and wired the Arduino to get it to work well.
You'll want a REAL TIME CLOCK module to hook up to the arduino, otherwise you'll have a hard time keeping the time correct.
I don't know of a ready made mosfet board that you can use to fade the LEDs. I used TIP 120 transistors to power the LEDs. I don't know if thats the BEST method, but it worked for me. Its a little different, because they operate off the negative leg of the power. And its really easy, only a handful of components.
I don't know what your electronics background is, but I have an Electrical Engineering degree, so I'll get pretty technical here. I can explain things more simply if you want, but if you're going the Arduino route, you'll have to know basic electronics to get everything to work.
Here's a rough diagram I drew up of how I wired up the LEDs:
The PWM output of the arduino powers the TIP120. I put a 2000uf capacitor on this leg which makes all the transitions SMOOTH as butter. If I didn't add the capacitor, then I could distinctly see the LEDs light up in "steps" of intensity, and I really disliked it. The capacitor makes it a pain in the butt to program, but the finished result is much better.
I don't know what size resistor you'll need. The way my code is written it doesn't really matter, because the arduino kind of calibrates its output depending on current readings. Depending on the voltage/current of your LEDs, you'll probably need a 4.7K-30K resistor. Something in that range.
LED ouput is mostly a function of amps, not volts, and they typically ramp up really quickly when you approach their operating voltage. For instance, they might be 10% power at 11.1 volts, 50% power at 11.5 volts, 70% at 11.8V, 90% at 12.1 volts, and 100% at 12.2 volts, but if you measure the current, you can tell exactly what power level they're running at, instead of depending on a narrow range of voltage to monitor their output.
To measure the current, I put a 1W 1 ohm resistor on the incoming power. This makes it easy, because the number of milivolts accross the resistor is the number of miliamps. For instance: 20mv at the resistor means there are 20ma of amps going to the LEDs.
Anyway, that's enough rambling for now. I'm sure there are easier ways to do it, but the method I used I think is about the cheapest way to do it, and it made a good end result for me with very few (and easy to get) parts.