Hello, New Guy here. I apologize in advance if this question has already been asked by someone. I am currently running a 75g reef with a Fluval 4 cannister filter. Recently my nitrates have spiked to 50. I have done several water changes ranging from 5g to 20g. Just this past Monday I did a 20g water change and changed out filter media and am still getting nitrate at 50. All fish, coral and sand sifting starfish seem to be thriving, however my snails and hermit crabs have all died. Below I will have my last two testing results. Any suggestions on what could be causing this or how to get the level down so that when I replace the crabs and snails I hopefully do not have this same issue?
12/26 and 12/30
Temp 78
Ph 7.8
Salinity 1.026
Nitrate 50
Nitrite 0
Ammonia 0.2
Alk 3.5dKh
Calcium 209/315
With the exception of the calcium as you can see the numbers remain consistent. The testing on 12/26 was done prior to a water and media change. I do not know when the nitrates started rising because my testing on 11/22 had the levels at 10. Due to being down with COVID for a month 11/22 was the last time I was able to test until 12/26. Like I said above all fish, coral and sand sifting starfish are thriving and not showing signs of stress.
12/26 and 12/30
Temp 78
Ph 7.8
Salinity 1.026
Nitrate 50
Nitrite 0
Ammonia 0.2
Alk 3.5dKh
Calcium 209/315
With the exception of the calcium as you can see the numbers remain consistent. The testing on 12/26 was done prior to a water and media change. I do not know when the nitrates started rising because my testing on 11/22 had the levels at 10. Due to being down with COVID for a month 11/22 was the last time I was able to test until 12/26. Like I said above all fish, coral and sand sifting starfish are thriving and not showing signs of stress.