Betta Fins Shredding After Water Change

[Aria]

My betta had never had any fin problems until moving to an older dorm on campus. (I'm a college student) After day one of having his tank set up, his fins were SHREDDED. (Hes a veil tail and they were ruined about halfway up)

In a panic I medicated him for fin rot, but having never dealt with it before I didn't know how soon to expect results. Over winter break, I brought my fish home, and saw no issues. Brining him back after break, fins shredded again. Curiously though, I did not treat him for fin rot just to see if it healed on its own in the same amount of time as when medicated. It did! Two weeks later and his fins look totally normal again, minus some of the ends missing, but everything has healed back together nicely and no more fraying or tatters.

It's getting close to water change time, and I'm afraid to change it because every time I do his fins become a wreck here! Could there be something in the pipes in this old building doing this to his fins?

If so, is there something I can treat the water with to prevent this?

I have a 5.5 gallon filtered tank.
Hes not shredding them on plants and decor because he NEVER has issues when home.
I treat the water with bettasafe I believe, and have never had a problem at home. (I live in a small town though and go to school in a city, maybe it's the city water?)
I clean the tank every 2 to 3 weeks with a full water change since its difficult to maintain a cycle while I travel back and fourth between home and school.

Could this be caused by high/low PH? Because if thats the problem I'd like to pick up PH Up/Down while I'm out today. Anybody have any ideas?

[Sena Hansler]

Don't mess with the PH. They can adjust to almost anything. Messing with it may cause more swings, and that'll lead to more stress.

I want to guess he is tail biting... Can you give us a picture of him currently? An uncycled 5 needs to be cleaned every few days to avoid ammonia spike. He may be stressed from that and moving around.

[Aria]

I thought he could be tail biting too, but if that were true I'd think he would only do that after a move from home to school. But here even after water changes his tail is still a wreck.

Currently his tail is fine, it's already healed so there's really nothing to show. When it tatters though it's very fast, int he course of a day it's all in strings and rips at the end.

After the initial first couple days of new water his tail is fine, and he's completely normal.

[Sena Hansler]

Well, I have tail biters. One in particular will bite and bite until I find out what is wrong. I had to have him in a 1 gallon since he stopped biting then. Now he started and I don't know why.

I don't think PH would be the problem for your guy. Have your water tested. You absolutely need to up your water changes. I recommend twice a week, since it is uncycled. The change (100%) from ammonia waste to clean water could cause stress too. I do two 50% water changes a week so I don't remove the fish, and can keep ammonia down.

[NorthernLights]

It may be that your fish stresses a great deal when you change the water. Do you take him out? Using a cup or a net? Or do you change the water with him in the tank, like using a gravel vac or siphon?