Sorry to hear about your loss. There isn't a reefer here who's been in the hobby for any length of time who hasn't experienced a tank crash. I went through one last year after I moved. It's a horrible helpless feeling to watch everything in your tank die faster than you can respond. This is an awesome community and you'll find lots of support here to help you get back into the reefing game. I've never met a more generous bunch of people.
Like others, I've used Red Slime Remover without problems, but I have heard that as the slime dies it can impact the pH and oxygen levels in the tank. Marine Depot has some really good info about this on its product description page:
UltraLife Red Slime Remover is a revolutionary time tested product, that will effectively and safely remove Red Slime quickly from all Coral and Invertebrates. UltraLife RSR contains natural cellular matter, select biological accelerators and special supplements proven effective in removing Red Slime from Corals and Inverebrates and is Safe for reef tanks, corals, invertebrates, desirable macro-algae, nitrifying bacteria and fish.
UltraLife RSR will accelerate the solubilization and biological digestion of organic solids. In the process, the oxygen uptake rate in your aquarium will increase as a result of this increased biological activity. It is very important that your aquarium is able to support this increased oxygen demand along with your aquatic life`s need for oxygen. Therefore we recommend increasing your O2 levels by the addition of airstones prior to and during treatment.
For best results, DO NOT turn off UV Sterilizer or Ozonizer. Continuation of Protein Skimming is recommended but may require adjustment.
Due to Increased biological digestion of organic solids we recommend increasing your O2 levels by the addition of airstones prior to and during treatment.
No need for Water changes or Removal of Carbon Filtration.
Safe for reef tanks, corals, invertebrates, desirable macro-algae, nitrifying bacteria and fish.
Treats up to 300 Gallons (1135 L) Net wt. .71 oz (20 grams)
Contains NO ALGAECIDES OR ERYTHROMYCIN SUCCINATE
KEEP OUT OF THE REACH OF CHILDREN
FOR AQUARIUM USE ONLY
Again, I'm really sorry for your loss. Don't beat yourself up about it. The delicate balance of nature is exquisite and no one does it better than Mother Nature. It never ceases to amaze me that despite the fact we used the ocean as a sewer and strip it of its resources, it still manages to hold on. How much more it can take I don't know. My hope is that the multi-million year evolutionary head start it has over humans will serve it well and it will be here long after we humans are gone.