LOL I have not seen 500w MH before. Ok, so the 120w led units are probably the same as 250w mh (give or take a lot, like are they 3w vs 1w, lenses, led types, etc etc) so take that into play. The nice thing is you can run them all day, less heat, less electricity, better spectrum. Over a 90g I think two would be plenty.
Full spectrum meaning?
I also know a lot of people who only had the white/blue Led lights had to supplement with T-5s to get the color they liked...
i'm one of those people that is currently debating between swapping out my white & blue fixtures for full spectrum or just getting 2x48" t5s to get the color.. so I agree with you here.
I recently went through the same debate. I just slapped 2 t5s over my canopy. I run them for 3 hrs a day. Until the debate on color combos are settled. I figured it would be the best solution. I like it so far
2 ai Sols..... I have a Blue plus and Purple plus.
I switched on Friday. So far so good. The things in my tank are open like never before.