Odd Nitrate Ready (at least for me)

[anachrotech]

I meant READING. sheesh - wish I could edit title
I've been doing either pre or post water change testing since January. Most of the post water changes had the nitrates between 5-10, closer to 10. Hard to read! This morning, my nitrate color was between 0-5, closer to 0. This may seem to be a stupid question, but should I be concerned?

Tank - 36g, Fluval 305 with ceramic bio-rings (2 baskets) and purigen (1basket)
Lighting - Current Plus LED 24"
Todays parameters - 0,0,<5
Other parameters tested before (not today) Phosphate btw .25-.50, Ph 7.6, GH 143.2, KH 71.6 (8,4)
Temp 78
Occupants: EBJD with suspected tumor (not eating much, not much waste except food he spits back out), 2 Mystery Snails, 4 Ghost Shrimp.
Gravel substrate, rocks, fake plants.
Weekly 50% water changes with gravel vacuuming-tap water w/Prime.

I did change the carbon in one basket to Purigen. Could this cause this drop? Or, more likely changing one basket from polishing pads/carbon to bio-rings (last month)?

ETA- Tested other parameters just now. Phosphate btw .25-.50, Ph 7.6, GH 125.3 and KH 53.7 (7,3)

 

[Rivercats]

As long as the tank isn't planted then don't worry about it. If the tank is planted you will need to have a nitrate reading of at least 10ppm.

Forgot to add that Purgen removes organics from the water which can indeed help lower nitrates.

 

[anachrotech]

As long as the tank isn't planted then don't worry about it. If the tank is planted you will need to have a nitrate reading of at least 10ppm.

Forgot to add that Purgen removes organics from the water which can indeed help lower nitrates.

Thank you. Good to know as I will move to planted sometime in the future. I wish I had the Purigen when battling to keep nitrates below 40