Anyone experience a phosphate spike after scraping back glass?

[CamoFan]

I noticed it as well. I've had low nitrate/phosphate because it was bound up in the algae (GHA, in my case). Removing a large quantity of it will typically spike my nitrate/phos levels as I assume that scrapping the algae causes the release as it decays or its through natural decay/waste products since the algae was the primary consumer. But, as someone else said, scraping the algae at water change time will typically help to alleviate this since it's vacuumed out.

If you have a .22 micron filter, anything that is free floating should get picked up fairly quickly. In an emergency, I've used phos blaster super nuker from Reef Results. It drops the phosphate down rapidly (I think it binds to calcium since it recommends to use a calcium buffer before using the phos blaster). It works extremely well by precipitating the phosphate out of the water.

 

[Miami Reef]

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!

 

[gbroadbridge]

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!

That's interesting.

Perhaps this means that filtration of particulates from the sample is necessary in order to achieve an accurate test result.

There may be a closer correlation between tests conducted with a Hanna checker compared to ICP with filtration.

 

[Dan_P]

That's interesting.

Perhaps this means that filtration of particulates from the sample is necessary in order to achieve an accurate test result.

There may be a closer correlation between tests conducted with a Hanna checker compared to ICP with filtration.

Interesting idea

 

[Dan_P]

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!

Great results!

 

[Timfish]

I haven't bothered to monitor PO4 levels when scraping sides of a tank but I actually do expect it to alter stuff in the water. This paper shows biofilms in a marine aquaculture system can sequester PO4.

 

[taricha]

Perhaps this means that filtration of particulates from the sample is necessary in order to achieve an accurate test result.

Interesting idea

@Lasse Has had some feelings about filtration before a hanna phosphate test.

 

[Garf]

Are those results not within the device error margins? I may be thinking of the LR Hanna though.

 

[Miami Reef]

Are those results not within the device error margins? I may be thinking of the LR Hanna though.

ULR is +/- 0.02ppm

 

[Lasse]

@Lasse Has had some feelings about filtration before a hanna phosphate test.

Generally - I have got nearly the same result as @Miami Reef - lower PO4 when using filter, 0.22 micron

Sincerely Lasse

 

[taricha]

Generally - I have got nearly the same result as @Miami Reef - lower PO4 when using filter, 0.22 micron

Sincerely Lasse

At one point I think it was discussed as to the use of lanthanum in the tank. Or are you just thinking calcium carbonate particles in general?

 

[A_Blind_Reefer]

That is the point of filtering the water taken from tha aquarium after scraping. If the algae residue is causing sample cloudiness (higher phosphate reading) or reacting with the reagent, filtering eliminates both effects. If the high phosphate reading remains after filtering, the effect is caused by something which is dissolved. e.g., phosphate.

I understood that. It was more to the point from the other comment about the free floating algae being mechanically removed quickly via a roller filter which would imply that no free floating algae particles were in the test sample the following morning.

 

[Dan_P]

I haven't bothered to monitor PO4 levels when scraping sides of a tank but I actually do expect it to alter stuff in the water. This paper shows biofilms in a marine aquaculture system can sequester PO4.

Neat. @Lasse has been trying to teach me about phosphate release from sediment, but alas, I am a slow learner. @taricha check out the paper.

 

[Lasse]

At one point I think it was discussed as to the use of lanthanum in the tank. Or are you just thinking calcium carbonate particles in general?

My thought have been more around particles that disturb the readings and that the acid environment in the test tube is able to dissolve loosely bound phosphate from the partially destroyed algal cells (after scraping), from organic matter and in some extend bound PO4 in minerals

Sincerely Lasse

 

[jda]

LC does not allow for accurate po4 tests from Hannah for at least a day, for me. I always imagined it was flocculant particles interfering with the light and photo diode creating less light transmission.

 

[Lasse]

LC does not allow for accurate po4 tests from Hannah for at least a day, for me. I always imagined it was flocculant particles interfering with the light and photo diode creating less light transmission.

Particle in the water (not only LC flocks) was the first reason why I test with filtered water

Sincerely Lasse

 

[Miami Reef]

LC does not allow for accurate po4 tests from Hannah for at least a day, for me. I always imagined it was flocculant particles interfering with the light and photo diode creating less light transmission.

It‘s because the reagent will break apart the lanthanum phosphate bond with the acid.

 

[Timfish]

Neat. @Lasse has been trying to teach me about phosphate release from sediment, but alas, I am a slow learner. @taricha check out the paper.

Well, keep in mind we can't test for or quantify particulate or dissolved organic forms of phosphorus. We also cannot test or quantify what's being sequestered by organisms that live in our systems. Some cryptic sponges, for example, will sequester polyphosphorus crystals in their tissue. As far as phosphorus being bound to mineral surfaces and released what needs to be taken into consideration are the roles of biofilms. A quote from introduction of this paper

"Many experiments have been conducted with mineral surfaces that can sorb
dissolved ions and organic molecules. It is well known that data, gained with
those mineralogical clean surfaces, cannot be simply applied and compared to
natural conditions. Organic matter is masking the original mineral surfaces and
thus, these surfaces change their sorption behaviour drastically."

As I see it all we can do is try to maintain what the corals consider acceptable levels of PO4. FWIW .03 mg/l is the minimum, .2 mg/l is what they are exposed to with upwelling .5 mg/l is acceptable and even .9mg/l might not be an issue. And jsut to help put these numbers in perspective, Rich Ross' acro dominate tank in his video "What's up with Phosphate" is sitting at 1.8 mg/l.

 

[Lasse]

Well, keep in mind we can't test for or quantify particulate or dissolved organic forms of phosphorus. We also cannot test or quantify what's being sequestered by organisms that live in our systems.

Exactly.

But

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

2) When I measure the PO4 - I´m only interested - as a reefer - of the orthophosphate - that´s the in water dissolved PO4 with other words. That figure shows me a snapshot of the PO4 circulation in my aquarium. its show me the snapshot of what is left of PO4 in the water when all uptake,absorption, production and releasing processes have done their work. The trend I see with repeated sampling shows which process pair that is temporarily dominant (uptake/binding or production/release)

3) It is important to stress that the amount leftover (not used PO4) in the water and different organisms reproduction rate decide which organism that will be most favoured. As an example - some dinoflagellates is known to be able to thrive in low orthophosphate water concentrations, some of them can migrate downwards in the sediment in order to access orthophosphate rich porewater and so on. However their growth rate is normally not as high as for different other forms of microalgae which means that these other photosynthetic microorganism will dominate in orthophosphate concentrations that they are able to use

4) My thought of these high concentration of free orthophosphate systems like my old system (PO4 around 2 mg/L) and Rich Ross (@Thales ) system is that there are other factors beside of orthophosphate left over and reproduction rate that favour corals domination. Factor as shadowing, area occupation, grazers and microelements

Sincerely Lasse

 

[Garf]

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.