Is my Hanna Phosphate checker misreading my levels?

[Jmas4]

Hello! I have two reef aquariums. Both have amazing coral growth of softies, lps, sps. There hasn't been an algae outbreak for almost two years now (Knock on wood). There is only some hair algae growth in my refugium but the display is clean. Due to this lack of algae and no new livestock I have been decreasing my frequency of nitrate and phosphate testing to about once every two months. Throughout this time the nitrates are hovering between 1-4 ppm using the red sea test kit for both tanks. And phosphate is reading 0.00. I didn't worry too much about this number because I know HI 713 has an error range of 0.04 ppm and there is coral growth and no dino.
Then I noticed that my reagent I have been using was the wrong one for the past year. I mixed it up with hanna copper test. I quickly went to the store to get the correct one. The box says HI 713-25 while the packet says HI713-0. Its the same reagent right? The 25 symbolizes how many packets there are.
When I tested my aquariums both read 2.50 ppm, the limit of the test. I even tested my freshwater planted aquarium which has green spot algae which is a sign of low phosphates and that also read 2.50. I do not believe these numbers are correct.
Any advice?

 

[Drich5150]

I use the phosphorus lr and thats not the reagent for that one. So not sure

 

[damsels are not mean]

Sounds like the checker is busted. try it on a fresh salt mix and see what happens? Also could try it on a tapwater salt mix. There is probably a little phosphate in your tapwater enough to react but it won't read 2.5 unless it really is busted.

 

[Jmas4]

It might also be the reagent? After I put it in the water gets really dark...
I found my 5+ year old useless api test. It measures 0-0.25 phosphate.

 

[Shirak]

I use the ULR phosphate checker HI774. The packets say HI774-0 and they also say Phosphate Ultra Low Range Reagent. So if your packets are correct for your checker then it's probably not the reagent. Could still be the checker. If it's turning really dark blue then I tend to think it is reading correctly as blue is the color it should change in the presence of PO4

 

[homer1475]

You could buy the standards, this will tell you if the electronics are working properly. I have the standards for all 3 of my checkers, and use them once in a while just to see if the meter is reading correctly.

 

[jmichaelh7]

As long as you don’t bottom out and get Dino’s ha

 

[Jmas4]

I use the ULR phosphate checker HI774. The packets say HI774-0 and they also say Phosphate Ultra Low Range Reagent. So if your packets are correct for your checker then it's probably not the reagent. Could still be the checker. If it's turning really dark blue then I tend to think it is reading correctly as blue is the color it should change in the presence of PO4

I really appreciate the help!
The reason why I think it's the reagent is because the water turns really dark almost purple and I can barely see through it. Shouldn't the darkness of the water be in relation to how much phosphate there is?

From what I remember (about 1-2 years ago) when I was using the correct reagent before I mixed them up, after I added the packet there was no visible color change. Perhaps there was some change not distinguishable for the human eye so the sensor picked up on the change of absorbance. This resulted in a reading ranging from 0.00-0.1 which is correct reef parameters. But never have i seen such a dark color until I just bought this reagent batch.

 

[Shirak]

I really appreciate the help!
The reason why I think it's the reagent is because the water turns really dark almost purple and I can barely see through it. Shouldn't the darkness of the water be in relation to how much phosphate there is?

From what I remember (about 1-2 years ago) when I was using the correct reagent before I mixed them up, after I added the packet there was no visible color change. Perhaps there was some change not distinguishable for the human eye so the sensor picked up on the change of absorbance. This resulted in a reading ranging from 0.00-0.1 which is correct reef parameters. But never have i seen such a dark color until I just bought this reagent batch.

Yes the darker the color the higher the phosphate. I run around .08-.1ppm and after the 3 minute timer the vial is just a very pale blue color. I like the idea of trying on a batch of freshly mixed saltwater. There might be a little phosphate but it should be minimal. I wouldn't trust running it on fresh water. Not sure the reagents will work properly in freshwater.
You could also try diluting some tank water with RODI 1ml to 9ml RODI and run it again. There was another member recently that found his phosphate was off the charts and was able to get an idea where it was by doing a dilution step. Of course this is only helpful if everything is working correctly.

This is one of those situations where having a 2nd test kit or LFS to check for you would be ideal. I wouldn't trust the API kit you have. If everything is looking good, I wouldn't take any drastic moves. You need to take your time and find out if the checker or reagents are bad, or the reading is correct.

 

[jmichaelh7]

So some of the reagents don’t mix with other Hanna checkers ?

 

[FishyFishFish]

Probably not this but I'll ask the question anyway....

Are you following the timings in the manual (i.e. 2 minutes shake and then 3 minute countdown)? If it's being left longer then presumably the color will be darker.

And you're using 10ml of water in the vial?


However, if you haven't tested for a year and the test sample is getting really dark when you mix it, then maybe it could be that it is that high.

 

[taricha]

if you are trying to decide whether the answer is zero (red sea kit) or 2.5ppm+ (hanna kit) then you can buy another cheap kit to check for certain. But I'd put money on the hanna packets being closer to right. (once you've re-read the instructions and double-checked your method)
If hanna generates very blue color and the red sea kit doesn't then it's not a checker electronic issue - one of the chem kits is expired etc.

 

[Randy Holmes-Farley]

Try the test on one new salt water.