I've seen some projects about led lights recently at school fairs - you could compare growth rates, polyp sizes, ect of two frags from same mother colony under led vs mh and have a control group under t-5 or something similar.
Also, temp fluctuations versus using controllers, analyzing different salt mixes and their impacts on a tank, coral foods, etc. there's all sorts of questions people are asking on reef central you could try to test out.