I am replacing my 4x65 watt PC with 2x175 watt MH and 2x54 watt HO 03. I have a mixture of fish and coral in my 75g, 48" tank. My question is between the two MH lamps, what K rating should I get? I was thinking of one 13K and one 20K. The LFS said the 13K was really close to bright sun light and the 20K gives off a tinge of blue. Otherwise I was just going to get both in 20K.