If you really want, you can do a 50-70% WC. But that should have been done a long time ago? Hopes this helps.
Glad the hear it went well. I think you have learned a valuable lessonrichy said:i did a 50% water change, and it looks like the fish are the inverts (10 amanos, 5 tigers) are all doing well. no casualties. the snails seem unaffected too. lesson learned. NEVER add liquid reagents near the tank where it can be knocked into the tank itself! thanks, all.