PO4 Test Kit Question?

[Bud's Reef]

The instructions say to shake the tube for 5 minutes, the card says 2 minutes, which is correct?

[elosusa]

2 minutes with a maximum time of 5 minutes. The maximum time is mainly for freshwater as freshwater will start to breakdown the chemicals and make the results unreliable after 5 minutes. Hope that helps.

[Bud's Reef]

Thanks, that helps a lot. My arm was a noodle after shaking it for 5 minutes. Next time two minutes it is.