Did I Accidentally Crash My Cycle? Nitrate Drop!

Hello!

I just did a water test and noticed something odd.
Yesterday, when I did my test the nitrates were almost 10ppm. I did a 25% water change and introduced my Betta to the tank the same day. I tested the water again today and saw the nitrates have dropped to below 5ppm, but not quite 0ppm (maybe 2-3ppm?).

Have I accidentally crashed my cycle by vacuuming the rocks on the bottom of the tank (removing any decaying fish flakes from my fishless cycle) as well as the water? Or is this sort of fluctuation after a water change normal?

Yesterday:
pH: 7.8
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 5-10ppm

Today:
pH: 7.8
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 0-5ppm

I'm using the API kit, as well as Seachem Prime and I've started the Seachem Stability treatment for good measure now that I've introduced the fish. 20L tank with heating and filtration. 25-26°C.

 

How old is the test kit? And do you bang the bottle (reagent #2) on a table a few times as well as shaking it?

 

How old is the test kit? And do you bang the bottle (reagent #2) on a table a few times as well as shaking it?

The test kit is from September 2018. And yes, but I'll give the nitrate test another try, this time really shaking up the bottle.

 

Bang that #2 bottle on a hard surface a few times (every time) because some of the ingredients precipitate out as solids on the bottom between tests.

 

I redid the test, this time shaking the 2nd bottle around like there was a diamond in there I was trying to shatter, and the results changed. It's a darker orange now, looks like almost 10ppm. Whoopsies! (*´∀`*)

Thanks for the help!

 

You will have a reduction in nitrates with a water change since you removed water and added clean water. So for a 25% water change your nitrates would go down 25%. 50% water change down 50%. The numbers are real hard to tell the difference so its around what I would expect.

 

That too ^^^

 

Any live plants?

 

This is one of the main reasons we do water changes. Most of our tanks never grow the bacteria that takes care of nitrates so they have to be removed with water changes. It is perfectly normal to get a reading for lower nitrates after doing a water change.

 

Not sure if we understand the problem. Nitrates of 40 and below are normal and safe.