Clams: pinched mantal

[Snowmaker]

ive had one crocea and one derasa that ive had for 8 months die with in the past two weeks and no changes to water params have happened and no new clams were added, the only thing that happened is that it got hot last week and the temp got up to 85.6. My sps also did not love that they all browned out but my montis. So would the temp have been responsible for causing too much stress???? I also have one crocea that ive had for a year and a half now that was not affected.