For whites, I am a big fan of BridgeLux Vero. For less money, better efficiency and easier assembly, use fewer LEDs at the expense of spread. My typical setup is 4 over a 48x48 inch tank - you could get away with 2. I added a 5th to see if it helped with my spread, it does not.
You will probably be happier with warmer whites and more blue. Cool blue and fewer blue leds for the same color temperature is more natural, more efficient and cheaper. But warmer whites bring out reds and yellows in fish and corals and work much better than trying to add red LEDs.
For Royal Blues, I am a big fan of the discontinued Luxeon 16 LED chips. But about $10 gets you a 100W Chanzon on
Amazon, which is useable. I run mine around 40 watts. No point downsizing to save money or for a better spread, unless you are real picky about dimming. I am not sure the lowest you can run them, but it is pretty low. For $10, I wouldn't hesitate to run them as low as 10 watts if you need the spread.
You do need some regular blue, and I'd recommend cyan (even though am not using it right now). Steve's, RapidLed or LedGroupBuy are good choices for 3 watts. You might get lucky and find something good that's 100w or 50w on ebay, alliexpress or
amazon. I've had better luck with finding good blues than good cyans.
I am not a fan of optic lens and I don't run anything between my LEDs and the water. This took some expensive trial and error to learn how close to the water I could keep my LEDs, although you could always error on the side of caution. I have an enclosed canopy and after trying this with passive cooling, learned I needed a fan.
A 48x48 tank is easier than a 48x24 to do this way. The closer to the side of the tank you are willing to go, the better your spread but the lower your efficiency. I think you are fine, but other people are much pickier about this than I am.
You should be able to do this barebones under $100 but a $500 budget is much more realistic if you want a quality set up.
