Help please.

[Loupe]

I have a 30 gallon(uk) tank and recently, a lot of fish have died. I do weekly, 20% water changes, and my test results(keep in mind this is about an hour before I do my water change so Nitrates might be a little high)
Amonia= 0.2 mg/litre
Nitrite=0.15 mg/litre
Nitrate=30mg/litre
pH=7 and a bit.

In the past month or so I have lost three platies, a guppie, two black widow tetras and a beautiful dwarf gourami.
I am left with
six zebra danios
three guppies
one black widow tetra
10 corys
one dwarf gourami

None of the dead fish showed any signs of disease or fin nipping. I don't overfeed, and have just got rid of an algae problem.
I have a Fluval Biolife filter, that is able to be used for tanks of up to 55 gallons. I also have a huge epedemic of snails.

 

[Angry_Platy]

From the values you posted, it doesn't look like your tank is cycled...there should be 0 ammonia and 0 nitrite....How long has the tank had fish for? Did you cycle it before adding fish? Was there ammonia/nitrites in the tank when the other fish died?

Also, how did you get rid of your algae? Did you use chemicals of any description?

If you can answer these questions we might be able to help you a bit better

 

[Loupe]

The tank is two years old. When I got it I didn't know about fishless cycling, so I cycled with the danios. To get rid of the algae i didn't use chemicals, I just gradually introduced more real plants to starve the algae out. The amonia and nitrite levels have been like that for a while. The test kit book says that the levels are acceptable but I still want to mget them down further.

 

[Angry_Platy]

All I can suggest at this stage then is to o water change and more often....maybe 3 times a week....every second day or so....you need to get the levels down...they should be zero (I am sure you know this)....perhaps the levels being as they were over time have affected your fish hence the deaths....

OR....Perhaps your fish died of old age??

Let us know how it goes

 

[plecoperson]

i dont think your levels are that high bearing in mind that you perform the test an hour before you remove ammonia/nitrite and stuff. mine goes to zero after ive done a water test.