Test kit accuracy and chasing numbers

[Reef Jeff]

I just bought a Hanna ULR Phosphate egg. Wow was I surprised when my Red Sea PO4 showed .08 and my Hanna showed 20 ppb (.02 ppm). That's a huge difference in the world of Phosphate control. Add the Red Sea PO4 to my list of "no longer use". It's no wonder many of us cannot agree on a decent PO4 level.

I hate when someone posts bad information so I have to admit when I do it (see above).

I just learned something new about the Hanna ULR checker which many of you probably already knew. It reports Phosphorus, not PO4. The conversion from ppb of phosphorus to ppm of PO4 is not what I thought. For example, 20 ppb on the Hanna checker should NOT equal .02 ppm on the Red Sea test kits as I thought. It is really 20 ppb of P = .061 ppm of PO4.

See this conversion table:
http://www.pny.se/aquarium/

So it turns out the Red Sea kit is accurate after all. My last test was 26 ppb on Hanna and .08 ppm on Red Sea so they show the same levels once the conversion is done correctly. I’m still glad I bought the Hanna because that digital readout is very nice compared to trying to read the colors.

Anyhow, the Red Sea kit is back on the good list in my eyes. Sorry for pulling the fire alarm.

 

[srad750c]

I hate when someone posts bad information so I have to admit when I do it (see above).

I just learned something new about the Hanna ULR checker which many of you probably already knew. It reports Phosphorus, not PO4. The conversion from ppb of phosphorus to ppm of PO4 is not what I thought. For example, 20 ppb on the Hanna checker should NOT equal .02 ppm on the Red Sea test kits as I thought. It is really 20 ppb of P = .061 ppm of PO4.

See this conversion table:
http://www.pny.se/aquarium/

So it turns out the Red Sea kit is accurate after all. My last test was 26 ppb on Hanna and .08 ppm on Red Sea so they show the same levels once the conversion is done correctly. I’m still glad I bought the Hanna because that digital readout is very nice compared to trying to read the colors.

Anyhow, the Red Sea kit is back on the good list in my eyes. Sorry for pulling the fire alarm.

Thanks for the chart, I’m going to Hanna cause I can never seem to read the Red Sea PO4. Not enough difference in the lowest readings.

 

[Reef Jeff]

Thanks for the chart, I’m going to Hanna cause I can never seem to read the Red Sea PO4. Not enough difference in the lowest readings.

You will like it...definitely worth the money. The unit only comes with enough reagent for 6 tests. You will want to order the refill reagent for 25 tests. I used 3 tests learning to use it the right way!

 

[srad750c]

You will like it...definitely worth the money. The unit only comes with enough reagent for 6 tests. You will want to order the refill reagent for 25 tests. I used 3 tests learning to use it the right way!

Thanks for the heads up, cause I would have been salty when I got it. 6 test will only last me a week, cause I like new toys. Didn’t read description when I ordered.

 

[JCM]

I'll bump this again. After resuming my normal feeding and water change schedule, nitrates are consistently at 10.

I also just received a hanna 713 phosphate checker. It's showing 0.00 ppm. Hopefully I'm using it correctly... hmm

 

[Reef Jeff]

I'll bump this again. After resuming my normal feeding and water change schedule, nitrates are consistently at 10.

I also just received a hanna 713 phosphate checker. It's showing 0.00 ppm. Hopefully I'm using it correctly... hmm

The important thing is to eliminate any air bubbles in the liquid and clean all fingerprints and lint off the glass before installing into the device to do the final measurement.

Curious if you would be willing to compare Hanna to Red Sea test and report if Red Sea also shows zero or close to zero?

 

[Randy Holmes-Farley]

I also just received a hanna 713 phosphate checker. It's showing 0.00 ppm. Hopefully I'm using it correctly... hmm

That checker has claimed accuracy of +/- 0.04 ppm, so even if used correctly it could be as high as 0.04 ppm. [emoji3]

 

[JCM]

The important thing is to eliminate any air bubbles in the liquid and clean all fingerprints and lint off the glass before installing into the device to do the final measurement.

Curious if you would be willing to compare Hanna to Red Sea test and report if Red Sea also shows zero or close to zero?

Thanks! After shaking for 2 minutes, I did tap as many air bubbles as possible out of it and wiped it down with a long free cloth to get it clean. I performed the test twice and got the same reading.

I don't have a red sea test on hand, but if I can get a hold of one I would be happy to compare.

 

[JCM]

That checker has claimed accuracy of +/- 0.04 ppm, so even if used correctly it could be as high as 0.04 ppm. [emoji3]

Yes, I noticed it said that in the booklet. Even 0.04 ppm seems low to me but perhaps that's correct. Thanks!

 

[Randy Holmes-Farley]

Yes, I noticed it said that in the booklet. Even 0.04 ppm seems low to me but perhaps that's correct. Thanks!

IMO, a good target level for most reef tanks is 0.02 to 0.03 ppm phosphate.

 

[JCM]

IMO, a good target level for most reef tanks is 0.02 to 0.03 ppm phosphate.

Sorry, I should've been more specific. I agree 0.04 is perfectly fine and a good target to shoot for. I meant it seems low for my tank. I just assumed it would've been higher.

 

[srad750c]

You will like it...definitely worth the money. The unit only comes with enough reagent for 6 tests. You will want to order the refill reagent for 25 tests. I used 3 tests learning to use it the right way!

Got mine yesterday, wow, I love it. Thanks

 

[Reef Jeff]

Got mine yesterday, wow, I love it. Thanks

Yep, I love mine too. Randy mentioned the error rate on the Hanna PO4 checker is .04 ppm. But the one you and I got is the URL which according to Hanna’s manual says that one has an error rate of 5ppb +\- 5%. So if we do the conversion to PO4 the error rate for the URL is .015 ppm +\- .00075. So essentially an error rate of .016 ppm max. That’s pretty precise for a hobby kit if that is really true.

I know you have the Red Sea PO4 kit. Would you be willing to compare Hanna to Red Sea test and report each reading? Just curious if you get the same as me. Red Sea can match sometimes or be off as much as .02 - .03 higher. Never shows lower for me.

 

[srad750c]

I trust Hanna phosphorus, but getting a little frustrated with Hanna alkalinity and calcium checkers. They give very low results compared to Red Sea Pro. RSP is spot on with Salifert. Think I wasted my money on those. Just can’t get trustworthy results. Results today were:
RSP
dKH 9.5
Ca 435 ppm

Hanna tested both twice today.
dKH 8.6, 8.4
Ca 369, 368

Who would ya trust?

Not much difference on PO4, approx. 0.05 ppm difference between RSP and Hanna.

 

[Reef Jeff]

I trust Hanna phosphorus, but getting a little frustrated with Hanna alkalinity and calcium checkers. They give very low results compared to Red Sea Pro. RSP is spot on with Salifert. Think I wasted my money on those. Just can’t get trustworthy results. Results today were:
RSP
dKH 9.5
Ca 435 ppm

Hanna tested both twice today.
dKH 8.6, 8.4
Ca 369, 368

Who would ya trust?

Not much difference on PO4, approx. 0.05 ppm difference between RSP and Hanna.

I’ve heard the same issues about Hanna calcium and alkalinity so I didn’t buy them for that reason. Since Red Sea was spot on with Salifert, I’d say you go with that number given the known Hanna issues. I’ve been using Red Sea Calcium with a calcium level maintained at 450 and have coralline growing, SPS Acro growth so I think your good with Red Sea numbers.

As for the Hanna Phosphorus vs Red Sea PO4, a difference of .05 is a lot really. If your target is, say .02-.03 and your test kits are different by .05, then you really don’t know what your PO4 levels are. I’ve done a few comparisons and once they matched but usually Red Sea reports higher PO4. Probably test error on my part the time they were about matched. Hmmm...hobby test kits...

 

[Reef Jeff]

I trust Hanna phosphorus, but getting a little frustrated with Hanna alkalinity and calcium checkers. They give very low results compared to Red Sea Pro. RSP is spot on with Salifert. Think I wasted my money on those. Just can’t get trustworthy results. Results today were:
RSP
dKH 9.5
Ca 435 ppm

Hanna tested both twice today.
dKH 8.6, 8.4
Ca 369, 368

Also...a good test will be to take a known volume of your water, say a gallon, add a small power head and calculate how much calcium it would take to raise that gallon from the Hanna result of 368 to to a target of, say 435. Then slowly administer the calcium over some time period enough to avoid precipitation from the addition and continue until precipitation occurs, if it even does occur. If we know what level typically results in precipitation at a given alkalinity level, then we can figure out how much calcium was added by the time the precipitation starts to get an idea which test kit was closest in the first place (or just do a Triton test and compare). If the Hanna was closest, we would expect no precipitation raising the level from 368 to 435, but if it is already at 435 and we keep raising it until precipitation occurs we could determine which test was closer in the first place?

We need @Randy Holmes-Farley to tell us if this test would be valid and give useful information about which test was closest to reality. Also, at what level calcium typically precipitates out of seawater. May be too many variables?

 

[Fábio Cruz]

Has anyone used Salifert's Strontium test yet? I found it very complicated and without much acuracy...

 

[Fábio Cruz]

Has anyone used Salifert's Strontium test yet? I found it very complicated and without much acuracy...

 

[srad750c]

Also...a good test will be to take a known volume of your water, say a gallon, add a small power head and calculate how much calcium it would take to raise that gallon from the Hanna result of 368 to to a target of, say 435. Then slowly administer the calcium over some time period enough to avoid precipitation from the addition and continue until precipitation occurs, if it even does occur. If we know what level typically results in precipitation at a given alkalinity level, then we can figure out how much calcium was added by the time the precipitation starts to get an idea which test kit was closest in the first place (or just do a Triton test and compare). If the Hanna was closest, we would expect no precipitation raising the level from 368 to 435, but if it is already at 435 and we keep raising it until precipitation occurs we could determine which test was closer in the first place?

We need @Randy Holmes-Farley to tell us if this test would be valid and give useful information about which test was closest to reality. Also, at what level calcium typically precipitates out of seawater. May be too many variables?

I will sell the Hanna Ca and ALK test, I been using Salifert for over 10 years, switched to RSP cause I used their Reef Foundations product for a while, plus LFSs carries them. Even the API KH is closer to RSP than Hanna, go figure.

 

[mitch91175]

Just a little side bar on testers. I would suggest having a 2 different manufacturers tester for what you are testing. Let me elaborate. I have been mixing my salt using a Milwaukee MA887 to check the salinity. Well I neglected to calibrate for a while and though that my new salt mixes were good to go at 1.025. Yesterday I upgraded from the Apex Classic to the Apex. After getting everything set and the COND probe in the water I got a reading of 43.8ppt which convert to 1.0331 SG. First thought was no way that is right. Then I thought ok calibrate the MA887 and test again and it definitely was correct on the Apex.

I freaked and started taking out water and adding in fresh RO/DI and adjusting the MAG/ALK/CAL as well. I ended up having to replace almost 40 gallons of water to get the salinity down to 1.0286 and will bring it down to 1.026 today.

Now my issue definitely could have easily been remedied IF I was calibrating every time before checking the salinity of fresh salt mixes. Yes I did loose coral and didn't know where to look after everything was SUPPOSEDLY in range.

If my PM2 didn't crash and burn on me and I didn't put in the Apex, I likely would have gone on thinking that everything was ok and that the coral lost was just simply I could not keep that particular coral in my display.

Moral to this story (at least for me) is to never again trust a single source for anything that I am measuring that will be supplemented or added to my display that REQUIRES a particular value. I personally cannot wait for the Apex Trident to come out so I can use it as my primary and my test kits as backup.

 

[mitch91175]

Another lesson that can be taken from my experience is to have what you need on hand if possible in case of an emergency. Think of it as not if I have an emergency, but WHEN I have an emergency how prepared will you truly be?