lighting question

[wku5]

I have a 4 bulb tek light inside my canopy on my 20 long sps tank. All my corals are growing great but on one side they will brown a little then when i turn em around itll color back and the other side will do the same. Does this mean my lighting just isnt good enough? i have thought about putting halides in there but idk which size i want or if i want mogul or de. any tips is appreciated.

 

[gchaney]

HOw old are the bulbs?

 

[wku5]

They are like 7 months but it seems to do the same thing when they are brand new.

 

[75 tanker]

dont think its your light, i think maybe the flow in that spot of your tank isnt good enough. check for a dead spot