You may want to change out the white bulbs for fresh ones. I know 8 months isn't a very long time but you can see if it helps and if not you can use the old ones fir the remainder of their life and still have the new ones for when you need them. Some fixtures have mediocre lamps.
You really should change out the filters in your RO
. If you have a 50gpd membrane or less you could upgrade it to a 75gpd one and get the correct flow restrictor to make sure it works. I once had my flow restrictor seize up on me and that raised my TDS
pretty bad until I got a new one. A 75gpd membrane has a higher rejection rate than slower ones so it'll make better water in addition to more. Just something to think about.
You could also try some ChemiPure Elite to help with the phosphates.