If your nitrates are potentially 80, you should do more than 50%. You want to get them under 20. I would recommend at least an 80% water change. If they don't go down, you will have to do another one until they do. But I don't know why they wouldn't.
Last time I did a 80 per cent change and nitrates stayed the same, not sure as to why. I will give it another go though and see what happens..
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When the tank is cycled I would do the biggest water change you can 12-24 hours before getting your new fish. Just suck out every last bit you can and fill it with new water (with proper dechlorinator of course) and do not re dose the ammonia.
I apologize, I don't agree with that...
The tank was fishless cycled and it needs the water change before adding fish. The nitrates are really high after a fishless cycle and the water change is the last step in preparation. We always recommend a very large water change at the end of the fishless cycle before adding fish. I don't see how this will destabilize anything at all.
I apologize, I don't agree with that...
The tank was fishless cycled and it needs the water change before adding fish. The nitrates are really high after a fishless cycle and the water change is the last step in preparation. We always recommend a very large water change at the end of the fishless cycle before adding fish. I don't see how this will destabilize anything at all.