70% water change after cycle nitrates still the same

[John mango]

hi ive done a 70% water change after my cycle has completed .nitrates still read the same as before the water change 40ppm. im using RO/DI water which has 0 nitrate. kind of stumped as i thought the nitrates would of at least halfed. can anyone help?
thank you

 

[Coralreefer1]

Your cycle has not concluded fully hence the elevated nitrates levels. I don’t want to perform water changes while your tank is cycling as it only prolonged the cycle.you have to be close to the end though!Good luck..

 

[Randy Holmes-Farley Verified Community Expert]

Your cycle has not concluded fully hence the elevated nitrates levels. I don’t want to perform water changes while your tank is cycling as it only prolonged the cycle.you have to be close to the end though!Good luck..

Im not sure he even has nitrate as it might be nitrite interference, but having nitrate is not a sign that ammonia cycling is incomplete and is not a reason to wait longer.

 

[Randy Holmes-Farley Verified Community Expert]

hi ive done a 70% water change after my cycle has completed .nitrates still read the same as before the water change 40ppm. im using RO/DI water which has 0 nitrate. kind of stumped as i thought the nitrates would of at least halfed. can anyone help?
thank you

I expect your kit just doesn’t have the precision and accuracy to detect the change.
Do you know if nitrate is zero? Nitrate may not be nearly as high as you think. A little nitrite can read as a lot of nitrate.

 

[IslandLifeReef]

hi ive done a 70% water change after my cycle has completed .nitrates still read the same as before the water change 40ppm. im using RO/DI water which has 0 nitrate. kind of stumped as i thought the nitrates would of at least halfed. can anyone help?
thank you

I looked at your other post and see that you were having issues with your cycle. It seems like you are around day 32 of your cycle but the product you used wasn't designed for that purpose. It may take longer for the bacteria that turn NO2 to NO3 to populate. You said before that your NO2 was 5 ppm. That is very high. What is it now? If you have NO2 in your tank, you will get a false high NO3 test reading.