Yep, I did that. Pasted their answer below....I guess I'll be OK if I end up having to use it. Some fish were flashing, I treated with PraziPro first, and they quit itching. So if it stays that way, I"ll save the Cupramine for later...
Seachem Support 100215 (Seachem Laboratories)
Aug 14, 10:41
Hello David,
Thanks for the email and for your interest in Cupramine. From feedback on other forums, the Cupramine will not stain acrylic tanks.
I hope this helps! Let us know if you need further assistance.
Seachem Support 100215