Tank looks great. The bubble alage would suggest high phosphate levels
You are Correct Sir!
Here's how my tank spent the summer:
1. My t5's apparently degraded nearly completely somewhere in the
ninth month of their life. It never occurred to me to worry before
a year.
2. My weekly water changes slowed to semi monthly (maybe).
3. I allowed phosphate magnets (foam, etc) to go uncleaned for
a couple of months.
Perfect recipe for phosphate