Alicetse,
1)I think you posted in the wrong forum because your tank is not considered a nano(at least not to New Yorkers) LOL
2)So are you keeping plants with the tank you mentioned? If so, what light is on it? If not, I can give you some info on using LED on planted tank and coral tank.
On average, if you use properly design LED fixture and 1-1.5W LED / gallon of water, your tank is considered at high light for planted tank and thus CO2 is needed. For a reef tank, beginner can use 1.5-2W LED /gallon of water for softies and LPS. Then, if you want very fast growth rate of SPS you can go up to 3W LED / gallon but DIMMER is a must, you can easily burn your coral with it. You can also search RC for a calculation of LED base on surface area since your tank's height falls within the correct zone of the method. If you tank is 30 inch, then the formula they provide will be incorrect.
3)To use T5 for planted tank, Hobby with 'The Planted Tank Forum" has a detailed chart what to use for what light level you want.
4)To use T5 for coral, they work for sure but don't under estimate how much they cost-an ATI 48" 8 bulb version is $800, not much different from LED implementation of similar light output. There are both pros and cons to either technology. Research more and BEST go to forum members' tank to see for yourselves. Oh don't go the extremist member starting with "J" or "D" in the members name because they will swear one technology over the other no matter you can prove to them. (It's an inside joke here in MR, LOL)
5)If setup correctly, keeping softies and LPS is even easier than planted tank. Of course, I am not talking about tank that keeps only 4 or 5 different type of plants. REAL Planted Tank hobbyists that collect over 30-100 different species of plants just like coral collectors.
6)Join a reef club in your vicinity that you can talk to hobbyists directly in person like the LIRA in Long Island