I know something is not right but I'm not sure what to do differently.
The tank has been set up since last June. I cycled it first and then added 4 platys. They were fine for a month so then added 2 guppies 5 tetras and a plec. One guppy died the next day.
Then i think the tank crashed. I lost the other guppy and 2 platys in 48 hrs. I did daily water changes and tested daily and it recovered although one more platy died after a few weeks but it hadn't looked well since the crash.
Tetras plec and remaining platy all were fine for a couple of months then i got 4 more platys and a shrimp.
Same thing happened. since Nov I've lost all 4 platys and 2 Tetras.
Now have 3 Tetras plec and shrimp. I'm scared to get any more fish.
It's a 70l tank. I do weekly 20% water changes. What else can i do?