Mistery in my QT tank (parameters)

[juanmanuelsanch]

So I was testing the water in my QT tank to find out that I have nitrites over 5 ppm and nitrates over 20. So I would consider this a pretty toxic water.

The thing is that the water is coming from my display tank which parameters are 0 nitrites and around 3 for nitrates.

So my question is, why such a difference? I did my last water change on saturday. So I dont know whats causing it.

There are no fish in the QT tank since the water change, since I was waiting for the new additions to come.

Also the QT has hosted 12 fish for about 3 months without many issues. But in that time the water changes were coming from a fresh mix instead of the main tanks since I was respecting fallow time.

The tank should cycled taking into account that I added sponges from day one from the main tank to the filter plus all the time that has already passed.

Any help is appreciated.

 

[thegrun]

Is there rock or anything else that could be leaching nitrates? Sponge filters can certainly increase nitrates. Is the water you pull out of your main tank being siphoned off the bottom of the tank where it can pick up nitrates?

 

[CSalty]

Do you have anything circulating the water?


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[juanmanuelsanch]

its a bare bottom with some pcv pipes. I have a waterfall filter, it makes enough water circulation and oxygenation...

 

[scooter31707]

You are getting an ammonia source from somewhere. When was the last time you clean the filter and if you did, how did you clean it? I made a mistake like that and clean my filter with ro/di water and cleaned it too good and it produced a mini-cycle.

 

[juanmanuelsanch]

havent cleaned the filter. I really dont know what it could be.

I dont have rocks, just pvc pipes. The water used is from the upper part of the main tank.

The filter is a cascade filter, it dosent make to much water movement, just oxygenates the water.