Standardized phosphate test solution.

jasonkola

New member
I was wanting to test how acurate my test kit was. I had heard it is good to calabrate a tist kit with a known solution. I searched arround some and did not find any one selling such a solution. Dose any one know where I can buy a test solution with say .1 mg/lt so I can check how acurate my kit is? Jason
 

Billybeau1

Premium Member
There is a big difference between 1 mg/l and 0.1 mg/l.

I doubt you will find an answer there, as we try to get below .03 mg/l to inhibit microalgae growth, if that is your goal.

What brand test kit is it you are asking about ?
 

Randy Holmes-Farley

Reef Chemist
Premium Member
The best way to evaluate a test kit is in seawater with the stated ion in it. Using a freshwater standard will not ensure the kit reads correctly in seawater.

Adding a little of the the Hach standard to tank water with little or no phosphate can be used. That is known as the method of standard addition. :)
 
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jasonkola

New member
So correct me if I am wrong. I can get me some distilled water. mix salt mix with it to normal salinity. And mix 10 parts salt water to one part 1 mg/lt phosphate solution to get a .1 solution. I am just planning to use this as a reference point to check to see if the test kit reads .1 on a known .1 solution. That way I know it is reading acurately. I actually plan to keep it under .05.
 

Randy Holmes-Farley

Reef Chemist
Premium Member
Almost. Mix 9 parts salt water to 1 part standard to get to 0.1 ppm.

If you detect no phosphate with tank water, I might use that instead of the DI water plus salt. It introduces other factors, such as organics into the mix. :)
 

jasonkola

New member
I do detect 0 in the tank water. but I suspect it may not be testing correctly. Thus the need to check the acuracy of the test kit. I tested near undetectable with my elos kit. And I had my lfs tested my water and told me it was at .1. So either my kit is giving me false readings. Or my lfs is. I suspect the latter. I want to check the kit to make sure. If I have a level of .1 and add that to the solution it will change the concentration of phosphate. So I am hoping the distilled water with salt mix added will work for me. Jason
 

Randy Holmes-Farley

Reef Chemist
Premium Member
You won't get any better of a test using DI plus salt that doesn't show any than you will with tank water that doesn't detect any unless you assume there is none in the DI plus salt, and that may not be true.

It would be easy enough to do both and collect more data. neither is a foolproof way to evaluate a test kit. :)
 
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