Hammer corals dying one head at a time

[DavidA]

During the last few weeks my once thriving hammer corals have been dying one head at a time. They are about a year old and the impacted corals have been primarily the lower hammers rather than those heads that are higher up. Typically a head will suddenly inflate minimally while the other heads on the same coral appear normal. A day later the head is retracted and by the third day is gone. There is no jelly present. So far about 4 hammers with at least 3-4 heads per coral have died (at one time, hammer poles filled in the entire bottom surrounding the remaining hammers in the pic below). When the losses started I dipped in Coral Rx and found small reddish brown flatworms not consistent with euphyllia eating flatworms. I repeated the dip after 5 days and during the last 2 weeks I have not seen any flatworms despite ongoing losses

The fish are reef safe- 2 clowns, a royal gramma and a ruby long fin wrasse. I have Pithos crabs and peppermint shrimp and have not seen either bothering the hammers. i have had no hitchhikers for at least 6 months

The PAR is 130 for the tall hammer in the back of the photo and about 100 for the hammers on the bottom. Other coral including torches, montis and leathers s are thriving, A derasa clam is also healthy.

Phosphate was as high as .7 last march. I lowered it slowly over months with GFO to its current stable value of .25. Interestingly, the hammers looked their best when the phosphate was .7. Nitrate runs 7, alk 8.3, salinity 1.025, calcium 440. I have an MP10 in the 40 gallon IM AIO. A few days ago I directed one of the circulation pump nozzles down to the lower hammers as the flow seemed low (but unchanged) for the lower hammers

Any ideas of cause and what I should do? Could it be the peppermint shrimp?

 

[Mr. Mojo Rising]

Personally I feel the par level is pretty low. Mine is in high lighting and doesn't stop growing