Stained Red Sea test vials: how to clean?

[Wrasse-cal]

Anyone know how to clean a stained red sea test vial? I left the results of a nitrate test in one vial, and it's stained a bit purple.

 

[EmdeReef]

Anyone know how to clean a stained red sea test vial? I left the results of a nitrate test in one vial, and it's stained a bit purple.

Usually only acid wash is used. You can start with vinegar or citric acid soak overnight then move to stronger stuff.

 

[Highgrade]

+1 I soak mine in a 50/50 mix of RO/DI and vinegar. Works great.