Missing fish

[reefgirl189]

In the last week I've had a royal gramma and a tail spot blenny go missing. Both fish were eating great and healthy. Now today one of my cleaner shrimp is missing.

Parameters are:

Temp 78
pH 8.25
Ammonia 0
Nitrite 0
Nitrate 0
Phosphate 0 (finding hard to believe as I've had a minor cyano outbreak lately)
Cal 420
Alk 8
Mag 1210

The only thing I've done is increase the flow on my tunze's by a measily 10%, but this was after the tail spot and gramma were already MIA. Both were relatively new additions, within the last month, but they were fitting in fine.

I checked my sump and overflows as best I could.

I found one larger hermit crab that could be a suspect but I've had him since I first added my CUC and he never caused issues before.

Anyone have any ideas? I don't want anyone else to dissapear.

ETA: I highly doubt I have a mantis or something in there. The only new LR I've gotten has been placed in the sump.