chemical reaction?

[whatcaneyedo]

Many different chemicals can cause a tank to crash if they are overdosed. Or if they are added to a low flow area directly over a sensitive invertabrate many could easily cause damage or even death. But if you only add a little at a time and follow the directions on the packages carefully you should be fine with essentially everything.

However a good rule of thumb is: if you dont test for it dont add it. Personally I prefer to just do water changes rather than add a lot of supplements... especially ones that have funny names.