Any added food will introduce phosphates, but this is a given cause we gotta feed our fish right?
So you need to take the pro-active stance by trying to eliminate as much phosphate & silicates as possible. If you already have a cyno problem, siphon out as much as possible during your routine water changes. RO
water is the first attack, rinsing frozen foods with RO
water, having adequate flow & turnover water volume, using a quality carbon that won't leech phosphates back into the water, using a phosphate reactor with either Phosban or Rowaphos media & regular water changes.
I also drip Kalkwasser which precipitates some phosphate.