Nitrite level remains very high for months


I have now had my freshwater aquarium for 3 months, and the nitrite level has been alarmingly high from the beginning. I then added sera bio nitrivec to the water for 10 days running and replaced the internal filter with an external filter, as I was told this was better due to the bacteria.

something is wrong with the filter if the nitrite level is still that high! The biological performance of internal and external filters is the same, provided the filters are comparably sized and equipped with the same filter materials. You can, of course, not compare an external filter equipped with a large amount of  sera siporax to a sponge cartridge internal filter.

When I did a test 2 days ago, the nitrite level was alright, but now, 2 days later, the test sample becomes dark red again. Do you have another idea, I would be very grateful for your support!

You should in any case change water very generously (up to 80 % twice daily in extreme cases!) until the nitrite level goes down. Do not "clean" the filter by any means while doing so! It is important that the filter provides plenty of settling area for bacteria (sera siporax as a biologically active main filter medium). Conditioning the water with sera aquatan and possibly sera toxivec is advisable not only for protecting the fish, but as well for the micro organisms.

Best regards

sera GmbH

Dr. Bodo Schnell


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