something is not right with my tank

[MrsBobHale]

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?

[EauRouge]

Why didn't this come up in my active convos

Sorry about your fish. What have the water readings been like? Did you quarantine the new fish? What do you mean by the tank crashed, was there a pH crash? Did the fish have any visible symptoms before they died?

[MrsBobHale]

Hi eau

I mean the ammonia readings went up and i presume the bacteria weren't coping. It fitted exactly with new tank syndrome.

I'll come back tomorrow with current test results. I've been out most of the week at school show.

Thanks