I took it to our local pet shop and they did liquid one, ive done a water change
i think it happened because i rinsed the filter media a couple water changes ago
You've not really given enough info to say exactly what is happening however ;
Only rinse the filter media in a bucket of water previously removed from your tank, do not use tap water as it kills the bacteria. Only clean the media enough to remove the 'gunge', do not over clean the media.
Get yourself a liquid test kit, API freshwater test master has worked well for me. Don't bother with test strips, they can be unreliable and work out more expensive in the long run. Keep a record of your results as well as a record of water changes and filter cleaning. This will enable you to have a better overview of what is going on in your tank.
A cycled tank will nearly always have nitrates; ammonia and nitrites should be zero. Keep ammonia below 0.25 ppm with small water changes to protect your fish (I'm assuming you have some fish). Unfortunately this slows down the cycling process, but is the downside of cycling with fish in the tank. Fishless cycling is often much quicker.
With fish in the tank, Prime is an excellent product to protect the fish from low levels of ammonia and nitrite when cycling and will not affect the formation of Beneficial Bacteria. Prime is helpful to get you through the early weeks but is not a substitute for good water testing and appropriate water changes.
Good luck with your tanks.
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