Anyone experience a phosphate spike after scraping back glass?

[Dan_P]

I’m assuming API phosphate test has a similar chemical make up to Hanna reagents (using API in a Hanna checker). If so I’ve got a bucket with a lanthanum phosphate combo which I could test, to see how much it changes the reading, if it’s clear or full of lanthanum phos particulates. Not gonna bother if nobody is interested though, lol. I’m thinking it’s probably irrelevant. I’m pretty sure there are many organisms that can obtain phos from bound calcium carbonate surfaces, not at all clear if they can do it with Lanthanum however.

Interested. If your lot of the API phosphate test seems to be behaving, a test of aquarium water without and with lanthanum phosphate would be interesting unless someone has already shown that the particulates interfere with the test.

 

[Garf]

Interested. If your lot of the API phosphate test seems to be behaving, a test of aquarium water without and with lanthanum phosphate would be interesting unless someone has already shown that the particulates interfere with the test.

Yeah, that will be easy enough.What dose of lanthanum would you suggest? I’ve got a load of this mix at the min;

 

[Randy Holmes-Farley Verified Community Expert]

Initial phosphate prior to scraping: 0.02ppm (tested without using syringe filter, straight from the display)

After scraping and letting the tank run overnight. All my samples were taken from the display.

Unfiltered:

Trial 1: 0.06ppm
Trial 2: 0.03ppm
Trial 3: 0.05ppm

Filtered using a nylon .22um syringe filter

Trial 1: 0.01ppm
Trial 2: 0.00ppm
(trial 3 wasn’t needed IMO)

Thanks everyone!

Nice experiment. Would be interesting to know the source of the difference, but I'd lean to fine particles of CaCO3 from the scraped coralline still being suspended in the water and dissolving in the phosphate test at the low pH in the test.

 

[Dan_P]

Yeah, that will be easy enough.What dose of lanthanum would you suggest? I’ve got a load of this mix at the min;

I suspect a strong effect. If you stirred up your bucket of lanthanum phosphate and added a drop or two of this suspension to a 5 mL sample of aquarium water, I bet we see something.

 

[Garf]

I suspect a strong effect. If you stirred up your bucket of lanthanum phosphate and added a drop or two of this suspension to a 5 mL sample of aquarium water, I bet we see something.

Ok, several tests done.

1) Checked API reliability with fresh saltwater at 35ppt measured exactly the same as when I worked out my calibration slope a few months back. ie +0.51ppm PO4

2) Measured my tank water at 0.31ppm PO4, Hanna LR (API reagents) corrected.

3) Added 2 drops of lanthanum / phos stirred precipitate from my sand regeneration bucket to my 5ml tank water -note- probable excess lanthanum Result 0.16ppm PO4 corrected

4) Added 2 drops lanthanum chloride solution to 5ml tank water, tested immediately - Result 0.14ppm PO4 corrected.

5) Added 2 drops lanthanum chloride solution to 5ml tank water, allowed to stand for 30 mins -Result 0.16ppm PO4 corrected.

To rule out turbidity caused by lanthanum reacting with alkalinity I Added this further test (yes the solution turned cloudy);

6) Added 2 drops lanthanum chloride to 5ml new saltwater, tested immediately - Result negative 0.03ppm PO4 corrected.

 

[Dan_P]

Ok, several tests done.

1) Checked API reliability with fresh saltwater at 35ppt measured exactly the same as when I worked out my calibration slope a few months back. ie +0.51ppm PO4

2) Measured my tank water at 0.31ppm PO4, Hanna LR (API reagents) corrected.

3) Added 2 drops of lanthanum / phos stirred precipitate from my sand regeneration bucket to my 5ml tank water -note- probable excess lanthanum Result 0.16ppm PO4 corrected

4) Added 2 drops lanthanum chloride solution to 5ml tank water, tested immediately - Result 0.14ppm PO4 corrected.

5) Added 2 drops lanthanum chloride solution to 5ml tank water, allowed to stand for 30 mins -Result 0.16ppm PO4 corrected.

To rule out turbidity caused by lanthanum reacting with alkalinity I Added this further test (yes the solution turned cloudy);

6) Added 2 drops lanthanum chloride to 5ml new saltwater, tested immediately - Result negative 0.03ppm PO4 corrected.

Way more interesting than I had imagined

 

[Miami Reef]

Ok, several tests done.

1) Checked API reliability with fresh saltwater at 35ppt measured exactly the same as when I worked out my calibration slope a few months back. ie +0.51ppm PO4

2) Measured my tank water at 0.31ppm PO4, Hanna LR (API reagents) corrected.

3) Added 2 drops of lanthanum / phos stirred precipitate from my sand regeneration bucket to my 5ml tank water -note- probable excess lanthanum Result 0.16ppm PO4 corrected

4) Added 2 drops lanthanum chloride solution to 5ml tank water, tested immediately - Result 0.14ppm PO4 corrected.

5) Added 2 drops lanthanum chloride solution to 5ml tank water, allowed to stand for 30 mins -Result 0.16ppm PO4 corrected.

To rule out turbidity caused by lanthanum reacting with alkalinity I Added this further test (yes the solution turned cloudy);

6) Added 2 drops lanthanum chloride to 5ml new saltwater, tested immediately - Result negative 0.03ppm PO4 corrected.

Great job, Bill Nye.

 

[Garf]

Great job, Bill Nye.

Is the Nobel prize paid in cash or installments? Lol

 

[Timfish]

Exactly.

But

1) First line in the instruction manual for ULR phosphorous meter in red

. . .

Sincerely Lasse

Just FYI, Hanna's ULR phosphorus is only testing for PO4 and then converts it to the equivalent value of P. It's not testing for particulate or dissolved organic phosphorus and doesn't give total phosphorus.

But as particulate phosphorus is an important source for corals wouldn't excluding it from testing giving an inaccurate picture of what's happening in reef aquaria?

Fig 4 from "Phosphorus metabolism of reef organisms with algal symbionts"

 

[jda]

If you used LC and are using Hannah for po4, let those vials sit for a while and you will get more accurate test results. The flocculant debris will settle to the bottom. Since the three minute time limit of the acid (citric?) to react with the sample is long gone it is still not as good as just waiting a day or two for the flocculant to get filterd or settle in the aquarium before testing.

 

[Randy Holmes-Farley Verified Community Expert]

Just FYI, Hanna's ULR phosphorus is only testing for PO4 and then converts it to the equivalent value of P. It's not testing for particulate or dissolved organic phosphorus and doesn't give total phosphorus.

But as particulate phosphorus is an important source for corals wouldn't excluding it from testing giving an inaccurate picture of what's happening in reef aquaria?

Fig 4 from "Phosphorus metabolism of reef organisms with algal symbionts"

it’s a bit complicated on which particulates actually make it into the plasma of an icp, but there’s no strong trend for icp to be showing higher values than kits, which fits the idea that organic P is not high enough to dominate measurements.

When a few folks in the past have tested phosphate and total P by kit (Hach total P), I have not noted much difference.

 

[jsker]

Some good reading here, thank you

 

[Timfish]

it’s a bit complicated on which particulates actually make it into the plasma of an icp, but there’s no strong trend for icp to be showing higher values than kits, which fits the idea that organic P is not high enough to dominate measurements.

When a few folks in the past have tested phosphate and total P by kit (Hach total P), I have not noted much difference.

Do you have links for those tests?

 

[Randy Holmes-Farley Verified Community Expert]

Do you have links for those tests?

No, sorry. It would be with a Hach PO-24 kit and might be found by searching on that term, but a quick search didn't turn them up.

 

[taricha]

I know that Oceamo measures PO4 chemically, and independently P with ICP. Christoph described the two measures as being pretty much in agreement in most cases.

 

[Timfish]

No, sorry. It would be with a Hach PO-24 kit and might be found by searching on that term, but a quick search didn't turn them up.

It would have been interesting to see what the feeding and maintenance procudures were. But as far as I can tell most of the tests we do are converting some or all, depending on filtering, of the particulate and dissolved organic phosphorus to PO4 so we can get an idea of the total P but don't really know the ratios. It may seem like splitting hairs for most, but as studies have shown species specific preferences for particulate or live foods, testing like @Miami Reef to determine particulate : dissolved P could be useful in determining issues with certain corals or whether certain corals would be good tankmates.

 

[Randy Holmes-Farley Verified Community Expert]

It would have been interesting to see what the feeding and maintenance procudures were. But as far as I can tell most of the tests we do are converting some or all, depending on filtering, of the particulate and dissolved organic phosphorus to PO4 so we can get an idea of the total P but don't really know the ratios. It may seem like splitting hairs for most, but as studies have shown species specific preferences for particulate or live foods, testing like @Miami Reef to determine particulate : dissolved P could be useful in determining issues with certain corals or whether certain corals would be good tankmates.

Not sure what you are saying, but normal phosphate test kits don’t detect most organic phosphates.

 

[Timfish]

it’s a bit complicated on which particulates actually make it into the plasma of an icp, but there’s no strong trend for icp to be showing higher values than kits, which fits the idea that organic P is not high enough to dominate measurements.

When a few folks in the past have tested phosphate and total P by kit (Hach total P), I have not noted much difference.

That may be a good thing depending on the dissolved organic P in a system.

Not sure what you are saying, but normal phosphate test kits don’t detect most organic phosphates.

I have misread some stuff then. The Hach PO-24 refferenced persulfate and I see I read through stuff too fast.

So ICP results may depend a lot on when a water sample is done with respect to feeding or even if particulate or live foods are fed to corals. There may be a close corellation between inorganic P and total P indicating very low particulate or organic P or a larger difference showing a larger percentage of particulate or orgainic P.