pH: 7.5
Nitrates: 0 ppm
Hardness: 180 ppm
Nitrite: 0 ppm
Ammonia: Unknown - kit ordered
KH/Buffer: 120 ppm
Water Temperature: 81F
Three gallon tank, filtered, heated. 50% water change monthly with gravel vacuum (nitrates/trites always "0 ppm" according to strips). Fake plants/decor. Filter inserts changed monthly. Single male betta and sometimes a snail companion. Mainly betta pellets (never more given than he will eat) with occasional blood worm treats (1-3x a week). Flow from filter is partially blocked with plant decor to try and keep the current low.
I have two (possibly related or not) issues:
1) I have had both a mystery snail and a nerite snail now in the tank - both acquired when quite tiny. Both have died after growing to near adult size (after several months). There seems to be plenty of algae in the tank but I have supplmented occasionally with algae thins if things seem "too clean". I am mystified why both these otherwise active and growing snails suddenly stopped moving one day, remained alive but motionless for weeks and then finally perished.
2) My Betta (Freddie) seems to keep getting fin rot (maybe columnaris??). The first time it happened he had injured a fin on a decoration (since discarded and new decor all touted as "betta safe"). Shortly after that appeared fully healed he started getting red streaks in his fins accompanied with a very slight shredded appearance. I treated him with Bettafix as directed and he seemed to get better. Now just recently after at least a few months since the last incident he has developed a whitish patch on his back on the left side and started to look shredded up and red again - much worse than before. He is also acting strangely (lying on the heater or ground under a leaf which is not his normal m.o., quit making bubble nests, occasionally zipping crazily around the tank) despite maintaining a very good appetite (eats normally and with vigor).
Does anyone know what might be the issue(s) and if the two are related? Often seems something "goes wrong" shortly after a water change too. Are there other contaminants to check for? I am using city water that has sat out for a month in a special jug for the tank and I also add some conditioner just in case. I gently scoop him out into the cup he came in while cleaning the tank (no contact) and slowly ease him back into the tank when done to prevent water/temperature shock.
Last night I started treating the tank with acquarium salt 1 tsp/gallon. Any advice or ideas on what is the problem(s) and how to solve it/them and keep it from returning would be greatly appreciated!