Hi there
I'm sorry your fish passed. It is most unfortunate but I think I may be able to shed some light on what happened:
According to my research, I think you may have overdosed your tank with sodium thiosulfate (sp?). That is the main ingredient in most all of the water conditioners we commonly see in aquaria. There are others but they are ALL toxic if overdosed. Below are the names of the products and what they do:
Aqua Safe - Turns tap water into pond water, immediately neutralizes chlorine and chloramines plus detoxifies heavy metals.
Aqua Plus - Tap water conditioner. Removes chlorine and chloramines. Neutralizes heavy metals. Coats, protects and promotes healing.
ACE (ammonia, chlorine, eliminator) - Neutralizes the harmful effects of ammonia, chloramine and chlorine. Safe and fast acting. Use when setting up a new aquarium, making water changes, or ammonia levels are high.
It seems that you only need to use one of these products as they all do the same exact things. Since you say that you used all three in your water, I can only assume that you used a standard dose (or more) for all three. Wich in turn caused a serious condition to form in your goldies gills.
In the future, try to read and understand all of a products instructions, methods of operation and the like before proceeding with its use. If your ever in doubt, ask someone here and you'll get very informative answers that will surely help.
Again, I'm sorry you lost your goldie....
Hope this helps,
Paul