I have a 120 gallon 4 ft tank set up, I am running 6 54watt HO T-5s 3 of the bulbs are 10,000 K 2 are 6700 K and one is 420 blue. I am also running CO2 and have a full bed of folurite and folurite red. I am starting to see the tips of my plants turn brown. Not all the plants just some. Looking for any ideas on why this is happening.