Three test kits, big difference

[rishma]

I think it’s been 5 years since I tested calcium at home. I find no need for it. Alkalinity tells me all I need to know. ICP a couple times per year confirms I’m not blowing it.

 

[areefer01]

As a Trident ACM and NP user my advise is to not try and compare results across test kits. Pick one as the source of record (automated device since you have one) and only run a manual test if you get back to back test anomalies. In most cases it will be obvious.

Other things to note with the Trident:

• Keep dosing lines away from the sample line
• Keep RODI top off away from sample line
• Reduce bubbles in the sample line area
• Calibrate 48 - 72 hours after reagent swap - you want consistent results, not spikes
• Calibration is typically needed between lot number changes, typically when replacing A, B, and C at the same time (6 month kits, newer ones anyway, have all the same lot numbers which is nice)
• If you are going to compare, pull water sample from same location as the Trident sample line, and collect it at the same time the automation is running.

 

[mcarroll]

In Chemical Oceanography, Milero has a "Needs vs Availability" table for micronutrients in seawater that's interesting in a number of ways.

For one, it make clear how N and P are such issues for us and at the same time why MG and Ca barely qualify for testing.

N and P have N:A ratios very near zero where Ca and Mg are into the hundreds.....so 5 or 6 magnitudes of difference in availability?