Red Sea Ammonia test

[swiss1939]

Anyone else notice their Red Sea Ammonia test always reads 0.2ppm when in fact it is 0.0ppm? I've been cycled for over a month, with crabs, snails worms, amphipods/copepods and a leather toadstool in my tank for this whole time all doing well. My Red Sea Ammonia test always shows 0.2ppm but I know its at zero because everything else is doing fine. I gave up trying to get a perfect 0 reading from it right after the cycle ended after seeing 0.2 for a week straight. Haven't tested it again for over a month until today where I figured I'd test it again just to see if it would finally ready full zero and its the same 0.2ppm.

Just curious if this is a common result from these red sea ammonia tests?

 

[fcmatt]

try some pure ro/di water at 0 tds and report back!

 

[sssky]

I have the same issue. I tested it with freshly mixed sea water using RODI water and it returns 0.2.
Now I basically do two tests, one with fresh sea water one with my tank water. And as long as they are same color I am okey.