ok here goes...
power leds - most desired because of less heat and much brighter sya
halide - intense lighting that will make your corals grow like weeds mainit ito needs chiller or fans
T5 HO - not as hot as halide some say it will give your corals pastel color needs fan or chiller
rule of thumb, 5W per gallon, so kung may 20 gals ka your lighting will be 80w... pero hindi naman to sinusunod eh ngayon pa na my leds na... a 50 watts leds will out shine a 70 watts metal halide... san kapa