Sherri, i dont know what happened with your tank but i had a similar instance with red slime. now this was 15 plus years ago and all i could thing of was my sand bed had gone
toxic. remember back in the day when we were still using undergravel filters... yea i have been doin it that long... wow i feel old!! anyway everything was going fine for about two years and bam one day red slime showed up. almost two weeks to the day after the red slime showed up CRASH i came home to a milky white tank all my fish were dead. the tank was 78deg, the salt was 1.022 and the ammonia was through the roof.
im thinking that was from the fish. but the one thing i do remember was that i had
used a algae fix which was recommended by the LFS. wish i had just done big water changes.
sorry for your loss i know and feel your pain. if there is anything i can do let me know
Robert