Be sure, I'm not shooting anyone down for attempting a tough anemone. I've had my share and have tried to add to the hobby's knowledge base about them. I love the giganteas and magnificas specifically because they are not only beautiful, but we don't know much about them. I was interested in their reproduction- magnificas can be split to possibly make a sustainable tank raised population, giganteas are internal brooders so they release fully formed baby anemones rather than eggs, so captive raised babies are a possible way to circumvent shipping stress.
These guys are pretty numerous in the wild limited more by prime location than collection. We know shockingly little about their reproduction, but it is a good bet that the ones producing the most offspring in the wild are the full grown 3+foot ones that are not the ones they collect for the pet trade. I'm just being honest about their survival rates (as best as I can estimate). Oddly the ones that bleach seem to have a slightly better chance of survival. (Could be that if they are healthy enough they can expel the zoozanthelle otherwise it releases something toxic from the stress or something crazy like that)
Just want you to know what a rare and valuable gem you have if either or both do make it long term. We know nothing about what takes them down or what would fix the problem. They are in such a violent environment in the wild, you will see them hanging off of rocks in the tropical sun or the rain at low tide or in tidal pools that must have huge temp and salinity swings yet getting to our tanks is too much for them. So, document what you do and how they act. Someday we will get a picture of what works if enough people are out there looking for the answers.