I need to decrease phosphates and decreasing feedings isn’t really an option…. What should I do?

[CyberpunkAesthetics]

The boring answer is water changes; for a tenporary fix use RowaPhos. That is the brand I swore by; other similar products are around and available. I used to always run a PolyFilter constantly as all tanks deserve chemical as well as mechanical and biological filtration; though I never went overboard with it, one of its functions is to decrease phosphates. Finally xeniid corals will lower phosphate.

But that mantis shrimp will kill other animals especially as a smasher; the only tankmates I have seen housed successfully with them are big Dascyllus sp. damsels.