Salifert Phosphate Test Kit???

[matt_work27]

I made the diy trisodium phosphate solution and was just trying to see at what ppm of phosphate my salifert test kit can pick up. I dosed around 0.2 ml of the phosphate solution into 1 gallon of saltwater (which should be about 0.05 ppm based on the 1 ml into 100 L raises by 0.01). And there is absolutely no color on the salifert test kit. How is this possible.

 

[Randy Holmes-Farley]

I made the diy trisodium phosphate solution and was just trying to see at what ppm of phosphate my salifert test kit can pick up. I dosed around 0.2 ml of the phosphate solution into 1 gallon of saltwater (which should be about 0.05 ppm based on the 1 ml into 100 L raises by 0.01). And there is absolutely no color on the salifert test kit. How is this possible.

Can you describe how you made the dosing solution? There's no fixed recipe.

 

[matt_work27]

Can you describe how you made the dosing solution? There's no fixed recipe.

2 grams of trisodium phosphate dissolved in 1000 ml of water

 

[Randy Holmes-Farley]

That fluid is about 1.16 g phosphate per liter or 1.16 mg/mL.

0.2 mL contains 0.23 mg.

Add into 1 gallon, that gives about 0.06 ppm.

so that’s about what you calculated.

I’d try adding a full mL to the gallon of tank water and see if that is detectable.

 

[matt_work27]

After adding 1 ml still no color, but after 2 ml between .25 and .1 ppm. But that would mean the solution is around 1/3 the expected potency ( maybe even 1/4). Or the salifert test kit is just not reliable at all. I looked up more reviews and it seems like they just dont work well. I am going to pick up a seachem phosphate test kit and see if i get more accurate tests.