beta fish water

Question
I have two betas.  The one has had tail/fin rot and I've been treating him with tetracycline.  His water turns pink after just a couple days of water change.  When I first got him his water turned pink--I thought it was the fake flowers my grandkids put in his tank.  Any thoughts on pink water?

Answer
Interesting, I have never had pink water, just cloudy green or brown. Perhaps it is red algae though. Maybe try a algae destroyer and see if that does anything. It will not hurt the fish and would not hurt the water, so I would advise trying that. Also, is the treatment colored, if so it is that. Are the fake flowers aquarium plants or household fake flowers? If  household than maybe the coloring is coming off, you should never put anything in the tank not made for aquariums or aquarium safe, if that is what they are if not no worries. Let me know how it goes.
                                           Rachel A.