Thoughts on causes of death (longish)

[moby da goby]

Well my black ick problem is moot now since my yellow tang will most likely join the fishies in the sky. What I'd like is some thoughts on what may have possibly caused the death. here are the events tonight.
-Freshwater dip with RO water warmed to same temp of the tank. Left tang in there for 3 minutes max. Replaced back into tank.
-Cleaned tank glass and brown algae growing on glass under the top level of sand.
-Added new aragonite sand in one area. Didn't rinse sand as I never rinsed it when I started the tank.
Hour later Yaz the tang was laying on his side breathing heavily . I caught him with the net, leaving him in the water and immediately did a water change thinking I somehow disturbed enough of the sand bed to raise the ammonia. Rest of the fish are absolutely fine, no struggling to breathe, simply carrying about their business.
Any thoughts on what happened? I have a few but no way to check them out.

 

[moby da goby]

pH as well as I'm beginning to think I didn't clean the bucket very well beforehand and there might have been residue from something else in there, cleaning chemicals for example.
Oh well, live and learn I guess. Practically sterilize everything I own before using it.
No hospital tank but after this I"m in the process of cleaning an old FW 10 gal for one now.

 

[beth]

Cleaning chemicals or something???????? It is ABSOLUTELY necessary that ALL items, including maintence items used in the hobby, MUST be deadicated to hobby use only. This means that buckets, hoses, nets, brushes, whatever is bought new and never used for anything other than hobby activities. NEVER EVER.

 

[moby da goby]

And I usually do have my own equipment separated from anything else but I can't exactly go blasting out to the store to buy a new bucket 10 pm at night. This city doesn't run on a 24 hour schedule. You make do with what you got. Now I know and I have some spares on hand for any future problems that I may run into.