I'm finally upgrading my two cubes to a 125g. It is a standard 6' 125g by oceanic. Right now I have 3 20" fixtures two of them are 150w sunpods and one nova extreme pro t5. The tank will be mainly lps with a few sps near the top. Right now my lights are 17" from the sand bed and everything is doing great. I'm just wondering if the extra 4" or so are going to make a huge difference? I also have a bubble tip anemone and a lta I'm sure they will just go were the light is good for them. I will eventuality buy new lightening probably a 72 t 5 fixture or 2 36's since I do have a canopy. Any help on what fixtures to buy or if my lights will work for now...... thanks