Daily Phosphate Swings; What am I missing?

[ReefHunter006]

This mornings reading was .1 ppm at 9am. 12/17/2020

 

[SamMule]

This is a very interesting thread. I had someone tell me that corals uptake phosphates at night. I think he said they release some during the day as well. That could explain the swings you're seeing. I wonder what @Randy Holmes-Farley has to say about this!
Also, I have noticed with my hannah ULR that the readings will vary depending on how long the mixture has been in the cuvette.
I was playing around with mine last week, and took 4 readings with the same cuvette. Don't remember the time spread, but it was only a few minutes between all of the tests.
.05, .03, .02, and .00.
Would be interesting to do some more testing and see how much of a difference mixing and "resting" (for lack of a better word) time makes.

 

[ReefHunter006]

This is a very interesting thread. I had someone tell me that corals uptake phosphates at night. I think he said they release some during the day as well. That could explain the swings you're seeing. I wonder what @Randy Holmes-Farley has to say about this!
Also, I have noticed with my hannah ULR that the readings will vary depending on how long the mixture has been in the cuvette.
I was playing around with mine last week, and took 4 readings with the same cuvette. Don't remember the time spread, but it was only a few minutes between all of the tests.
.05, .03, .02, and .00.
Would be interesting to do some more testing and see how much of a difference mixing and "resting" (for lack of a better word) time makes.

That’s interesting, I will have to mess around with that and record what I find. I use Alexa to time everything. So when I press the button at the C1 stage my intervals should vary less than 20 seconds between tests each day. I will try extending and shortening that in a couple scenarios. Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

This is a very interesting thread. I had someone tell me that corals uptake phosphates at night. I think he said they release some during the day as well. That could explain the swings you're seeing. I wonder what @Randy Holmes-Farley has to say about this!
Also, I have noticed with my hannah ULR that the readings will vary depending on how long the mixture has been in the cuvette.
I was playing around with mine last week, and took 4 readings with the same cuvette. Don't remember the time spread, but it was only a few minutes between all of the tests.
.05, .03, .02, and .00.
Would be interesting to do some more testing and see how much of a difference mixing and "resting" (for lack of a better word) time makes.

I don't know if this is generally true or not, but here's one comment:

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1977.22.2.0301

"Typically, the hermatypic corals took up reactive P in the light and released organic P regardless of light conditions. Only Hawaiian P. compressa, incubated in seawater containing atypically high phosphorus levels resulting from human sewage eutrophication exhibited diel reactive phosphorus uptake and no total phosphorus loss (which, as is discussed later, could mean that these corals do not require particulate P)."

 

[Dan_P]

Here a pic of the tank as well to help show the lack of algae.

I see what look to be two big Mexican turbos. I would guess they are doing their job. I have 15 in a 75 gallon aquarium and they are about two inches in diameter. They eat an 8x8 inch sheet of dry algae in two hours every day.

 

[ReefHunter006]

I see what look to be two big Mexican turbos. I would guess they are doing their job. I have 15 in a 75 gallon aquarium and they are about two inches in diameter. They eat an 8x8 inch sheet of dry algae in two hours every day.

Yea plus some cerith, Nassarus, a fresh batch of trochus babies, limpets, and maybe 15 various hermits.

 

[BigSkyRich]

It does make sense that if you test right after feeding (before your tank has had a chance to process the food) you would get oddly high numbers but i'm not too sure, hopefully someone else can chime in and be more helpful

Fwiw rodi (even 0 tds) never touches my curvettes. Distilled only. I learned this while doing thorough research on how to properly use the Cal checker and just carried it over to the other checkers as well.

Interested on knowing more about the difference you experienced using rodi vs distilled. I use rodi and thought I was ok. What advantages with distilled?

 

[xxkenny90xx]

Interested on knowing more about the difference you experienced using rodi vs distilled. I use rodi and thought I was ok. What advantages with distilled?

Steam distilled water is cleaner than rodi and will get you more accurate results. An rodi with all brand new filters should be fine but after it has had some light use the water is not pure enough anymore for the Hanna checkers imo (even if it's 0tds water).

 

[BigSkyRich]

Steam distilled water is cleaner than rodi and will get you more accurate results. An rodi with all brand new filters should be fine but after it has had some light use the water is not pure enough anymore for the Hanna checkers imo (even if it's 0tds water).

Thanks. Looks like a comparative investigation is on the horizon. Good thing I have solar batteries in my vacation rental. Plenty of distilled laying around

 

[anth]

My tank is the same, phosphate before feeding in am is 0.03ish and then later in the day after feeding its between 0.06-0.09.
some days the low reading is 0.05 ish.
I too have wondered how everyone has a stable number.

 

[ReefHunter006]

My tank is the same, phosphate before feeding in am is 0.03ish and then later in the day after feeding its between 0.06-0.09.
some days the low reading is 0.05 ish.
I too have wondered how everyone has a stable number.

Glad to see I’m not alone!

 

[Randy Holmes-Farley Verified Community Expert]

Interested on knowing more about the difference you experienced using rodi vs distilled. I use rodi and thought I was ok. What advantages with distilled?

The need for distilled only relates to the calcium checker and its poor design that has it freakishly sensitive to very small levels of calcium in the blank. 0 ppm TDS RO/DI is perfectly adequate in all other Hanna tests, and often is adequate in the calcium one too, depending on how well the RO/DI is really working.

 

[Randy Holmes-Farley Verified Community Expert]

Steam distilled water is cleaner than rodi and will get you more accurate results. An rodi with all brand new filters should be fine but after it has had some light use the water is not pure enough anymore for the Hanna checkers imo (even if it's 0tds water).

That is just not true, IMO. You are inappropriately extrapolating from a bad Hanna design (the calcium one) to other kits.

 

[BigSkyRich]

The need for distilled only relates to the calcium checker and its poor design that has it freakishly sensitive to very small levels of calcium in the blank. 0 ppm TDS RO/DI is perfectly adequate in all other Hanna tests, and often is adequate in the calcium one too, depending on how well the RO/DI is really working.

Thanks for that Randy - I have slowly been transitioning to the Hannah checkers - currently have calcium, alk and phosph - thinking about the PH - calcium checker only one that is "freakishly sensitive"

 

[schuby]

Using distilled water in my Hanna Calcium checker made all the difference. It was way off when I was using RO/DI that must have had about 100ppm of Calcium in it. After reading somewhere (probably on here) that we should use distilled water for this checker, I tried it and it has been very stable ever since. I really dislike the titration test: the vials get fouled very quickly and it seems to be much more effort and time.

 

[Randy Holmes-Farley Verified Community Expert]

Using distilled water in my Hanna Calcium checker made all the difference. It was way off when I was using RO/DI that must have had about 100ppm of Calcium in it. After reading somewhere (probably on here) that we should use distilled water for this checker, I tried it and it has been very stable ever since. I really dislike the titration test: the vials get fouled very quickly and it seems to be much more effort and time.

If you had 100 ppm calcium in your RO/DI, you should throw the RO/DI away. 0 ppm TDS RO/DI will have much less than 1 ppm calcium in it.

The problem is that even very tiny calcium levels in the blank show up like a lot of calcium due to the multiplier effect that the method they employ uses.

 

[BigSkyRich]

The need for distilled only relates to the calcium checker and its poor design that has it freakishly sensitive to very small levels of calcium in the blank. 0 ppm TDS RO/DI is perfectly adequate in all other Hanna tests, and often is adequate in the calcium one too, depending on how well the RO/DI is really working.

so interesting results from a comparative analysis. Calcium with distilled: 476ppm; Calcium with RODI: 454ppm. Would have expected the inverse results given the conversation

 

[Randy Holmes-Farley Verified Community Expert]

so interesting results from a comparative analysis. Calcium with distilled: 476ppm; Calcium with RODI: 454ppm. Would have expected the inverse results given the conversation

No. The problem is that a trace of calcium in the blank leads to a low aquarium reading because it multiplies up the blank to a nonzero value, and then subtracts that nonzero value from the aquarium water.

That siad, the device claims only +/- 6% accuracy, so the 476 ppm is +/-29 ppm and the 454 ppm is +/- 27 ppm, so they are indistinguishable according to the Hanna specs.

 

[BigSkyRich]

No. The problem is that a trace of calcium in the blank leads to a low aquarium reading because it multiplies up the blank to a nonzero value, and then subtracts that nonzero value from the aquarium water.

Oh, so when it first calibrated prior to introduction of sample it has already factored in the calcium? Chemistry is what kept me out of the hard sciences

 

[BigSkyRich]

Oh, so when it first calibrated prior to introduction of sample it has already factored in the calcium? Chemistry is what kept me out of the hard sciences

so to add to that line of thinking, I should most definitely switch using RODI in the blank when storing and switch to distilled?