Question about nutrients and Dino’s

[mjuarez7]

Hey guys I have a 120 gallon reef tank and honestly I’ve gotten a bit lazy with my water changes haha, I usually do a 20 gallon water change weekly but now it’s probably monthly. Recently I noticed I got Dino’s in my sandbed I have a microscope I will leave some pictures below if I can possibly get an ID and some help beating them. My nutrients are sitting at
Nitrates: 2ppm (Salifert)
Phosphates: 0.31 (Hanna ULR)
With my nutrient sitting so imbalanced should I start doing water changes ? I also am running a refugium in my sump about 7 hours every night should I reduce the photoperiod or just stop the refugium completely? Thanks in advance

 

[Reef Jedi]

Following for ID knowledge. I’m sorry I can’t be of more help. I beat them in the past by out competing them with copepods and phytoplankton.