The puffer is especially sensitive to bad water parameters so I would say your nitrates are not as high as the test is indicating. Just for peace of mind and to eliminate the possibility, I would still take a tube of your tank water over to your LFS
and have them test it.
Another test...take some of the tank water and place it in a bucket. Test. Now dilute it with either distilled or plain RO
water and test again. We don't care about the salinity as you aren't going to add this water back to the tank.
When I say dilute, take about a 1/2 gallon or so of tankwater, place it in a 5-gallon bucket and test; then, dilute it with about 2-3 gallons of distilled water or pure RO
water (no salt)..you want a very definitive dilution. Mix it in well and test again. If you use a half gallon of water at say 160 (Nitrates) and dilute it with 3 gallons of pure water, that is equivalent to, if my math is correct, an 85% water change and your nitrate reading should then be around 40.
This is what I am looking at...using the pure water (either distilled or RO
) will answer the question if there are nitrates in your replacement water. It will also allow you to determine if dilution is actually working.