Hanna Phosphorus checker unreliable ?

[DE FISH]

My Hanna phosphorus checker is so unreliable I’ve just done 4 tests back to back and got the following

152ppb
121ppb
59ppb
89ppb

test procedure is down to a tee had the checker for a good few months I’m going through reagents like money is no object it’s a joke spending a good hour of my evening to try and get results that are similar

any suggestions or anyone having the same issue

I take the water from the middle of the dt with a syringe and fill to the line every single time

it’s getting to the point I just want to take a hammer to the checker and break it into oblivion

 

[GazS]

I had issues with mine until I tried:
Cleaning the beaker with microfibre at each stage.
Inserting with the hanna 10ml facing forward each time.
it is v sensitive to micro bubbles and marks on the container.

 

[fishface NJ]

I have never had a problem. I check mine every other day and it's always in the same ball park. I am using ULR HI736 checker

 

[fishface NJ]

I had issues with mine until I tried:
Cleaning the beaker with microfibre at each stage.
Inserting with the hanna 10ml facing forward each time.
it is v sensitive to micro bubbles and marks on the container.

that is the correct way to do it

there are three videos for the following on youtube: 774, 736 and 713. step by step

 

[DE FISH]

@GazS I do exactly the same as yourself I ensure cuvette is throughly cleaned and facing the same way each time as for micro bubbles I can try turning everything off and then taking a reading I don’t see any bubbles though looking like ima have to fork out for the calibration standard

 

[chadfish]

Since you are taking the sample from the middle of the DT, the problem might be suspended solids. To the naked eye it may look clear, but there (should be) a lot of stuff floating around the tank. If there's a place in the system with a filter, I'd try directly after the that. Or you can also get these little filters that go in the end of syringes. Amazon has them but you could probably find them even cheaper from lab supply. I
ht tps ://ww w. amazo n.c om/Syringe-Filters-Filter-Diameter-Ks-Tek/dp/B087LYP829/

 

[DE FISH]

I had issues with mine until I tried:
Cleaning the beaker with microfibre at each stage.
Inserting with the hanna 10ml facing forward each time.
it is v sensitive to micro bubbles and marks on the container.

I have never had a problem. I check mine every other day and it's always in the same ball park. I am using ULR HI736 checker

Since you are taking the sample from the middle of the DT, the problem might be suspended solids. To the naked eye it may look clear, but there (should be) a lot of stuff floating around the tank. If there's a place in the system with a filter, I'd try directly after the that. Or you can also get these little filters that go in the end of syringes. Amazon has them but you could probably find them even cheaper from lab supply.

Good shout can try taking the sample from the filter return that I run a small amount of floss and carbon through

 

[chadfish]

I have never had a problem. I check mine every other day and it's always in the same ball park. I am using ULR HI736 checker

Yeah me too. You could have a defective unit. Ever drop it? Maybe warrantee?

 

[DE FISH]

Yeah me too. You could have a defective unit. Ever drop it? Maybe warrantee?

Never dropped always taken care of as if it were lab equipment it’s around 4 - 6 months old it’s very odd :/ I’m going to try and and take the sample from the return and see if that helps I’ll run another two tests taking my tally to 6 packets used today lol

if the readings are way off from one another I’ll order new cuvettes and their calibration standard and see what happens will report back shortly

 

[Reef.]

Last week we had a very similar thread, the OP stated they were following the instructions to the letter, after a couple of replies he realised he wasn’t.

if you are following the instructions to the letter then you have either a bad packet of reagents or your checker is broke, as getting 152 and 59 reading is crazy.

Have to say mine is great but I do a couple of extra things, such as fill the tubes with Rodi water when being stored and line up the tube the same way each time and use a good microfibre cloth to wipe.

 

[Dan_P]

My Hanna phosphorus checker is so unreliable I’ve just done 4 tests back to back and got the following

152ppb
121ppb
59ppb
89ppb

test procedure is down to a tee had the checker for a good few months I’m going through reagents like money is no object it’s a joke spending a good hour of my evening to try and get results that are similar

any suggestions or anyone having the same issue

I take the water from the middle of the dt with a syringe and fill to the line every single time

it’s getting to the point I just want to take a hammer to the checker and break it into oblivion

Are you shaking the mixture of powder and water sample at least one minute and letting it stand 3 minutes? If yes, contact Hanna support before buying anything. The Checker might be broken.

 

[jesspal]

I hate my phosphate checker, I simply don’t have any confidence in my ability to follow the instructions or how well it’s calibrated.

The alkalinity checker is a dream.

 

[KrisReef]

Test results 1 &
2, back to back, just to help the OP have confidence that this can be done.

(Note- the pH checker is new to me and I’m not sure I did the test correctly- it looks low? But it was repetitive +-0.1. I’m going to find the new directions that I seem to have lost, 4 drops?)

 

[attiland]

Are you shaking the mixture of powder and water sample at least one minute and letting it stand 3 minutes? If yes, contact Hanna support before buying anything. The Checker might be broken.

Just for the record you have to shake it for 2 minutes before you let it stand for 3. Just because we are talking to the letter process.

 

[fishface NJ]

Test results 1 &
2, back to back, just to help the OP have confidence that this can be done.

(Note- the pH checker is new to me and I’m not sure I did the test correctly- it looks low? But it was repetitive +-0.1. I’m going to find the new directions that I seem to have lost, 4 drops?)

Yes four drops on the PH checker

 

[fishface NJ]

 

[KrisReef]

pH uses 5 drops

 

[fishface NJ]

You are correct 5 not 4

 

[DE FISH]

Ok everyone so i turned the skimmer off to reduce micro bubbles in the sample and took the sample from the filter return first test 89ppb sounding good right ? Second test cleaned out vial with Rodi 0tds refilled vial with water from the return to the line on the vial cleaned before c1 and again once after the reagent was added and shaken came out at 60ppb so today we have had


152ppb
121ppb
59ppb
89ppb
89ppb
60ppb

following the same procedure to the tee

 

[fishface NJ]

could the battery need replacing? Your number keep going down