Teresa..... your way is the BEST way. But since I didn't think Sue was open to that idea by her humorous comments, I was suggesting the next best idea
It takes time to tear down a tank, kill/sterilize the live rock and sand for re-use, set it back up and wait for the 4-6 week cycle. During that time the QT tanks need to be maintained for water quality - and it's a lot of work tending to uncycled QT tanks for that length of time. If it's an option, it's undoubtedly the best way to go. A more expensive way is tear the tank down, toss the live rock - or use it in a reef/fish-only tank - and purchase new live rock to cut down the cycle time.
The ONLY way to be sure no hidden pathogens are lurking in the tank (which includes the pods, etc) is to sterilize everything. The next best thing, which makes the tank "safer" (but not 100% safe beyond a doubt) is the suggestion I made.
Sue, the most common issue is Vibrio infections. Other pathogens, internal parasites can also be an issue. Nothing can be confirmed without an examination by a pathologist.
Many are of the belief, and evidence does support the fact, that Erectus may carry a species-specific variation of Vibrio or a pathogen that other species have no immunity to. This is supported by the fact most, but not all, of those who have failed with mixed tank had Erectus involved. Either the Erectus were added first and all other species perish shortly after they were added or the other species were in the tank first and after Erectus were added the first species (which were fine and healthy) suddenly died shortly after the addition of the Erectus.
There are really two ways to go. The option Teresa initially gave which really is the best way.....sterilizing the tank and re-cycling and adding EITHER the Reidi or the Erectus. Not both - you'd have to decide which you'd want in that main tank. The other option would make the tank "fairly safe", which is pulling either the Reidi or Erectus now, doing many huge water changes and sterilizing of the equipment while letting the rock/sand in the tank. You'd have no re-cycle with the 2nd option and the tank "should" be "safer" for either the Reidi or more Erectus at that point.
There is also a third option....... you could assume the Reidi did indeed die from an aptasia sting, and one could assume the Erectus died of an internal problem and not a pathogen at all. If that were the case, then nothing needs to be done with the main tank.
Since there were no outward signs of disease from what you've said, I can't honestly say I would tear the whole tank down...even though that is the best route to go for bona-fide pathogen issues. Again, for myself, I would at least seperate the species (only because I've been burned in the past and lost A LOT of money) and siphon/clean as much as I could, clean out the filtration, and do bunches of water changes. If, after adding another horse or two issues arose again, then I'd know I chose the wrong path and would then have to gut the tank and start over. I wouldn't do it at this point though since it's not a confirmed pathogen/disease issue.
Sue, unfortunately there are no "you must do this" rules. You have to do what you are most comfortable with. What I may be comfortable in doing you may not be comfortable doing. Again, many different ways to get the same end results in the aquarium hobby. We can only present options for you. The rest is up to you
Tom
wow.... another rambling post by Tom LOL
