Can't keep Betta alive

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Aquarium Advice Newbie
Mar 2, 2024
About a year ago I got a nice 15 gallon aquarium It ran for a while with some tetras I got from someone who was tearing down their tank. I let the tetras live out their lives but never added any more fish(minus some Amano and cherry shrimp that became a snack for the serpeas and a lesson for me)
The last fish dies, tank sits mostly empty for a couple months, heater and filter running. I discover there is still an amano shrimp running around in there.
I want to get it running again. I do a couple water changes, about 15% each week for 2 or 3 weeks. all params look good, and lone survivor's shed skin is spotted. he's still in there doing shrimpy things. ready for some fish.
I take my kid to the LFS only to discover it has shut down so we go to the big chain. I get a Betta, an algea eater and a Mystery snail. Algea eater is dead within 3 days or so. Betta acts really lethargic and dies about 7 days later. I test parameters, solid. I figure must be bad luck from big chain fish store. I get a warranty betta(and some ghost shrimp), same deal. super lethargic, stuck against filter intake( I put a prefilter on that to try to reduce flow, still stuck). Dies about 7 days later.
I test again. Here's the stats;
15 gallons. part of the tank is a filter with large sponge, some ceramic doughnuts I bought years and years ago. and I added Seachem Matrix after betta1 died.
a few plants, some algea, poorly contained Java Moss outbreak.
Temp 82F
Ammonia - 0
Nitrite - 0
Nitrate - 0
PH 7.5
Alkalinity 180
Hardness 150
Chlorine 0

I tested myself with master kit, and the person at the petCOrporation confirmed my numbers. I treat water with Seachem Neutral Regulator on changes, doing about 10% each week or so, each time one died.
What do I do now? 3 fish, albeit from the same shop, dead shortly after arrival. Really not sure what to do here.
Your aquarium sounds like an all in one tank, similar to a fluval flex. Maybe it is a fluval flex 15.

I have kept a betta in one of those tanks, but in reality the flow rate was probably a little too much for a betta. I had plenty of aquascape and I directed the output nozzles so they directed the water flow upwards so the water flow is broken up and slowed down.

Im also going to question the water parameters. Your fish produces ammonia, the ammonia turns the ammonia into nitrite and the nitrite into nitrate. In a cycled tank you see nitrate in your test, in an uncycled tank you would see ammonia and/ or nitrite. You see nothing which is practically impossible. This would suggest a problem with your water testing and you could have a water quality issue you arent aware of. I understand you got the water tested at the store, but do they really know how to do a test properly? It could just be that the fish died before water quality deteriorated enough to show up in your tests though.

There isnt really much to go on really. Your water parameters should be safe, but i do have a slight concern about accuracy. Poor water quality could manifest as lethargy. The temperature is a little too high for a betta, and warmer water holds less O2, so lack of O2 would also manifest as lethargy. But bettas are labyrinthine fish and can get air by breathing at the surface if needed. Perhaps as said, the flow rate is too high and the betta is just wearing itself out trying to swim against the high flow.

I would stop with the neutral regulator product. Trying to chemical alter water is a pointless exercise especially when trying to lower pH. It usually causes more problems than it solves.

What water conditioner are you using?
Good info here .. I suspected the water flow was a problem so I aimed the filter output nozzle upwards.

Neutral reg was used to remove chlorine... Is that a bad use for it?

I got the same results testing at home with a master kit.

I don't have an air stone. I thought that bettas didn't need one and figured the plants would give off enough oxygen. The Betta did seem to be hanging at the top of the tank with large gill movement towards the end.
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