Conflicting phosphate test results

[DirkCourage]

I’m trying to get a handle on my phosphate levels, but have been confronted by odd test results. Not trying to chase numbers, but suddenly feels like I’m flying blind. Tank has been running six months, and everything seems happy. No algae outbreaks. Weekly water changes and nitrates run between 5-10.

I’ve tested with RedSea Pro since startup and have been consistently read .1-.12 on the dial (with 17ml tank water test.)

I picked up the Hanna Phosphate ULR and get .9! (Confirmed twice.)

I took a sample to my LFS and was told .35 They were crazy wrong on other parameters, so I really don’t trust that number either.

I don’t understand the divergent results, or that they would seem to be out of line with my relatively low nitrate levels. Any suggestions?

 

[josephxsxn]

Ethier one or both using expired reagents?

 

[DirkCourage]

Ethier one or both using expired reagents?

Brand new kits, dates are good.

 

[guylaga]

On the Hanna, are you mixing the vial after adding the reagent for two minutes and then clicking the button for the three minute countdown?

 

[Shirak]

Also if you are new to Hanna, make sure the vial is wiped completely of fingerprints. Also can be helpful to orient the vial in the same direction for C1 and C2. You can use the letters at the top of the vial but mine have rubbed off so I made a small mark

 

[DirkCourage]

Yes for the Hanna I am following the exact instructions. I use the Hanna Alk and Ph testers, so I am used to using them. I wipe the cuvettes with microcloth, though I'll pay attention to their orientation next time. I guess the Hanna questions kind of cut to the jib here. This should be the most accurate test, but .9 is max value right? So it's technically telling me it may be higher. I've got a WC tomorrow, I think I'll try diluting 50/50 tank and RODI water for a sample and see what happens. And test RODI just to check the baseline.

 

[Shirak]

.9 is max for the Hanna ulr phosphate tester yes. What did the lfs use to test? The Hanna should be most accurate yes .. if it’s working properly and the only way to check that would be the calibration vial they sell. Worth checking the RODI just in case. Sorry no other good suggestions other than run the tests again or try yet another test kit?? :/

 

[MikeTheNewbie]

If you have a pipette, you could try diluting the sample with RO.
Eg 3.5ml sample + 3.5ml RO water instead of the regular 7ml sample and then multiply the result by 2.

 

[josephxsxn]

Do you get 0.9 even if you don't put reagent into the test tube? I wonder if there's something on the lens inside the meter.

 

[Shirak]

I had a weird reading on the Hanna once when I clicked the button too fast and went right from inserting to reading. The vial had a ton of tiny microbubbles I guess from the reaction of the reagent and the shaking. Hence the need to wait and let the fluid clear. OP said he was following the directions though so I dunno. Possible it's over .9ppm and the Hanna is correct.. or the Hanna is not reading correctly for some reason. Diluting the tank water would certainly give you a lower reading but doesn't answer the question if the tester is functioning properly

Could try a different vial. I had one that I would swear the glass had a blue tint even empty, clean, and dry... I tossed it as it was giving screwy results. Now I use one vial and make sure it's the same vial each time. Yes the checker is supposed to adjust for differences on C1 but I don't trust it if the glass is blue to start.

 

[Uncle99]

.9ppm with a Hanna, that’s 9 times your Red SEA.
If your system looks good, I would suspect test error of some sort.
Great idea, Test some new saltwater, that may shed more light.
Weird.....and annoying.

 

[Reef.]

Try testing fresh salt water, most have a little PO4 in I think so you should get a low reading from it, at least you will then know the Hanna is reading low levels, if that is the case I would trust the Hanna as accurate.

 

[Dan_P]

I’m trying to get a handle on my phosphate levels, but have been confronted by odd test results. Not trying to chase numbers, but suddenly feels like I’m flying blind. Tank has been running six months, and everything seems happy. No algae outbreaks. Weekly water changes and nitrates run between 5-10.

I’ve tested with RedSea Pro since startup and have been consistently read .1-.12 on the dial (with 17ml tank water test.)

I picked up the Hanna Phosphate ULR and get .9! (Confirmed twice.)

I took a sample to my LFS and was told .35 They were crazy wrong on other parameters, so I really don’t trust that number either.

I don’t understand the divergent results, or that they would seem to be out of line with my relatively low nitrate levels. Any suggestions?

Just to clarify, you sampled the aquarium water, took 17 mL of the sample and tested it with Red Sea, getting a 0.1 ppm PO4 reading. Immediately afterward, you took 10mL of the same water sample and ran a Hanna test and it read 0.9 ppm PO4. Is this right?

 

[DirkCourage]

Thanks everyone, good suggestions. I'll run some neutral tests with the Hanna, at least confirm that's working. Maybe I just got a lemon. I ran RedSea tests and Hanna within a few days, so I'll do a little more due diligence. Try a different cuvette.

 

[DrMMI]

Did you try running a high range test with red sea? I had an issue where I kept getting 0.08 on red sea. It wasn't an exact match, but it was the closest color. I checked with a Hanna and I came to find out, my phosphate were significantly higher than 0.16 and I should have been doing the high range test with the red sea.

 

[DirkCourage]

Did you try running a high range test with red sea? I had an issue where I kept getting 0.08 on red sea. It wasn't an exact match, but it was the closest color. I checked with a Hanna and I came to find out, my phosphate were significantly higher than 0.16 and I should have been doing the high range test with the red sea.

Well, INTERESTING results today to say the least. First off, performed the high range RedSea test and read .12 (x17 means that PO4 is 2!) Next up, a RODI test on the Hanna. I messed this up a bit, but I definitely got a reaction. I was prepping for a WC so I tested my new saltwater (same RODI from the LFS.) I got a reading of .3. Tested again with low-range RedSea and was around .1.

1) It looks likely my RODI supply has phosphate. I’m going to check this again, but there’s some logic to the readings then. It would explain why my nitrates are stable at 5, but phosphate wouldn’t move. I’ve been replacing PO4 with PO4, and adding it via my top-off as well. If this has been going on for months then of course this number is going to be high. The weird test results were weird I assumed my RODI was zero. I’ll check again, but this is going to be an interesting conversation with the LFS.

2) The RedSea high range test makes it clear. The Hanna was peaking out. PO4 is way high. I’m not running a skimmer, and I’m running a AIO nano so there’s no room for a reactor. I’m going to pickup some Phosban as I understand it can just go in a media bag. Any other advice is appreciated.

 

[josephxsxn]

If you had a skimmer I would recommend Lanthium Chloride, But without a skimmer to remove it I'm not really sure what the impact would be to a tank as I have never heard of one using it without a skimmer. But some folks have used 10 Micron socks but I don't think that will look good on a AIO.

What is your RODI setup like? What is your RO input pressure? Attached a photo of mine, it goes somthing like...

Well Water Bladder
Booster pump (to hit almost 90PSI)
10 Micron sediment filter
1 micron sediment filter
1 micron carbon filter
RO Membrane
Cation DI Resin
Anion DI Resin
Mixed DI Resin
Holding Barrel

 

[Reef.]

Well, INTERESTING results today to say the least. First off, performed the high range RedSea test and read .12 (x17 means that PO4 is 2!) Next up, a RODI test on the Hanna. I messed this up a bit, but I definitely got a reaction. I was prepping for a WC so I tested my new saltwater (same RODI from the LFS.) I got a reading of .3. Tested again with low-range RedSea and was around .1.

1) It looks likely my RODI supply has phosphate. I’m going to check this again, but there’s some logic to the readings then. It would explain why my nitrates are stable at 5, but phosphate wouldn’t move. I’ve been replacing PO4 with PO4, and adding it via my top-off as well. If this has been going on for months then of course this number is going to be high. The weird test results were weird I assumed my RODI was zero. I’ll check again, but this is going to be an interesting conversation with the LFS.

2) The RedSea high range test makes it clear. The Hanna was peaking out. PO4 is way high. I’m not running a skimmer, and I’m running a AIO nano so there’s no room for a reactor. I’m going to pickup some Phosban as I understand it can just go in a media bag. Any other advice is appreciated.

if that is 0.3 and 0.1 and not 0.03/0.01 then your water is full of PO4...or you are doing the tests wrong but probably not that.

 

[DirkCourage]

I don’t have my own RODI unfortunately, and can’t (apartment.) I buy it from my local fish store, a long-standing business. I’m fairly convinced their water isn’t up to snuff. I have another option nearby, so hopefully will get this sorted one way or the other.

 

[Reef.]

I don’t have my own RODI unfortunately, and can’t (apartment.) I buy it from my local fish store, a long-standing business. I’m fairly convinced their water isn’t up to snuff. I have another option nearby, so hopefully will get this sorted one way or the other.

Rodi units can be stored in a cupboard until needed, no reason why being in an apartment should stop you, it hasn't stopped me.