they all died; had 2 sets of power compacts and one stopped working for 2 days , replaced it with 4 T5 bulbs and left one set of the power compacts running ; the yellow released and floated to the back and later died , then the big green started going inside out ,then the small blue started turning inside out , then lastly the big blue went inside out ; sand is about 3 to 4 inches , 65 gallon tank . The first 2 on the left were in the tank first and doing great eating whole krill shrimp every other day , the other 2 never took the shrimp. Lights are on from 1 to 8 , sometimes an extra hour. Temperature was at 80 degrees when i first put the t5's , put 2 fans and got it down to 74-76 degrees.