Hello everyone. So, many of you know, I am fighting a losing battle with fin rot in my betta. Just typing out that sentence has me in tears haha. I've tried several treatments with breaks in between. He heals and gets worse. Now not even my most aggressive treatment is working which is telling me that, once this course is finished, it's time to stop medication. I'm leaving tomorrow for four days for unexpected vacation. I have someone coming in to look after the fish. I am already not enjoying this vacation because I am so worried about V. When I return, if he is still alive and not so ill that euthanasia is imminent, I plan to break down his tank. I was going to do it sooner but I wanted to finish the meds first and the last dose will be administered while I am away (I already have it prepared). With the break down, I am thinking about using RO/DI water for V to see if that helps. My tap water is actually not very hard (GH = 6 drops, KH = 3 drops, pH 7.6 ages to about 7.4) and its buffering capacity is pretty poor as you can see. It's actually reached a point where I started researching radical intervention surgically. Hah. I won't get into that, it's insane. What I need to know about is RO/DI water. V is a betta, I know they like softer water. Assuming the RO/DI water is neutral pH - do I still need to add buffers and such? I'm guessing yes but I'm not sure how to do this without elevating the pH. Every KH buffer I've read about (not pH modifiers, I'm talking about the actual mineral salts) raises pH at least somewhat, right? I'd like to keep the pH as close to ideal as possible. Could I use the water as it is? I'm really unfamiliar with this stuff. I'd appreciate any insight.