Thanks for your response! I will replace my bulbs as they are 1 year old so that may be part of my problem.
I was told not to use Carbon filtration when I originally set up my tank but do not remember why.
High PH and/or hard water may turn out to be my problem. I am not sure how to test for phosphates.
Here are the results of my latest test. I use RO water and do regular water changes 10-20% per week.
Hardness (GH) 280
Alk (KH) 50
Any suggestions are welcome…