Daily Phosphate Swings; What am I missing?

[Randy Holmes-Farley Verified Community Expert]

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

I would use RO/DI in the blank, yes.

I'm not sure what you mean by storing. I'd store the cuvettes dry.

 

[Randy Holmes-Farley Verified Community Expert]

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

Yes, it is effectively "subtracting" the absorbance of the blank, and any calcium in the blank means it is subtracting a larger absorbance number number than it should be.

 

[BigSkyRich]

I would use RO/DI in the blank, yes.

I'm not sure what you mean by storing. I'd store the cuvettes dry.

Mmm, ok. I read somewhere to store the corvettes with rodi to minimize any residual left on interior, but certainly cleaning and drying would accomplish that as well

 

[Randy Holmes-Farley Verified Community Expert]

Mmm, ok. I read somewhere to store the corvettes with rodi to minimize any residual left on interior, but certainly cleaning and drying would accomplish that as well

Well, I suppose that is a reasonable plan, but it is not the norm for a lab.

Here's how a lab would treat a cuvette:

Handling, Cleaning & Storage of Cuvettes of Spectrophotometer

Learn how to handle and clean the cuvettes of Spectrophotometer.

www.pharmaguideline.com

 

[BigSkyRich]

Well, I suppose that is a reasonable plan, but it is not the norm for a lab.

Here's how a lab would treat a cuvette:

Handling, Cleaning & Storage of Cuvettes of Spectrophotometer

Learn how to handle and clean the cuvettes of Spectrophotometer.

www.pharmaguideline.com

Well, a process well worth trying to emulate thanks, as always, for sharing your knowledge

 

[ReefEngineer]

@ReefHunter006 Great subject!! Have you been continuing to check and log your daily PO4 swings? If so would you mind sharing?

 

[Gogo007]

I have the same problem but my nitrate are about 0.25 always and phosphate is swinging up on feeding i deal with phosphate with lacl3 so normal i swings between 0.2 and 0.02

 

[ReefEngineer]

@ReefHunter006 Just curious how things are going now since all this time has passed.

 

[ReefHunter006]

@ReefHunter006 Just curious how things are going now since all this time has passed.

There have been a lot of developments in the last two months(we bought a home) that have thrown my tank into disarray.
Prior to September, I was getting swings still but on a small scale. For the last 7-9ish months prior to September I would maintain a weekly average of .03 ppm PO4 if tested every Sunday at 9am. I would fluctuate about .02 around that number testing later in the day.

i haven’t materially changed my feeding habits or nutrient export in that time.

 

[ReefHunter006]

Wanted to add some notes to this.

My thoughts on PO4 have changed significantly since I started in this hobby years ago.

Originally, I always felt it was alluded, but maybe not directly said, that PO4 and Nitrate tend to be correlated some what. Feed more they both will rise, feed less they both will fall etc.

Then I started testing both daily. I would watch PO4 go from .22 to .06 in 24 hours, while no3 would stay 1.6 to 1.8ppm. Both were tested with hanna for months.

This posed an interesting problem because it seemed like the advice I was getting was that you should monitor PO4 and watch for trends over the long term and be careful of swings.

I don’t think many people realize how much their PO4 swings within 24 hours. I mean testing directly after feeding would peg some days the PO4 at .2 and then two hours later it would have already dropped to .12. Within 24 hours it would be .03.

The point I am trying to make is that PO4 is changing rapidly in the home aquarium, and is not as dependent on nitrate as I originally believed.

What I have done for my frag only systems as of last month is spread out feedings over smaller doses, instead of one larger dose when I get home and PO4 stays much more consistent between .05-.1. No idea if this has yielded benefits yet. I only started about 3 weeks ago. It’s possible PO4 swings don’t have a significant impact and the culprit for GFO related deaths is actually GFO messing with alkalinity and not because it is stripping PO4 to fast. That last statement is just speculation, I haven’t used GFO in a year. Edit: you don’t want zero because of Dino’s. I meant the last sentence to mean a quick drop from .2 to .03 may not be a stressor event in its self. That’s speculation on my part.

I do know that if PO4 swings are a stressor event for SPS then I would investigate PO4 closely by testing at more regular intervals on the short term to understand the foods impact.

I should add details about my regiment:

Frag system - 100 gallons sps dominate no fish. Shrimps, hermits, snails only.

daily unless specified other

Morning
-2.5 ml each of reef nutrition phyto and oyster feast.

- 1 cube of frozen low micron food like calnarius or cyclopods

Evening
- 2.5 ml each of reef nutrition phyto, oyster, roti feast, and ROE.

- 1 cube of low micron frozen food

- every three days 1/16 teaspoon of benepets or reef blizzard.

- 10ml total of brightwells low micron liquid foods. I forget the names. I’ll have to look it up

- 10 ml of Red Sea AB+

 

[Lasse]

This is an interesting thread and it is in some ways opposite to my experiences. I normally get the highest readings in the morning before the lights switch on. This is IMO the most common situation because the production of dissolved PO4 (in the water column) is depended of the bacterial production of orthophosphate (dissolved phosphate) that ongoing 24/7 while the consumption (by corals and algae) only happens when the light is on. My tanks is heavy populated by corals, hence a high photosynthetic activity.

I can see two possible explanations for your experiences.
1. Your food contain free (not organic bound) PO4 that will be Immediately dissolved into orthophosphate (the type of PO4 Hanna checkers reads off). As an example I know that reefroids and some frozen foods can contain this.
2. Tiny particles in the water disrupts Hanna's reading of the sample, alternatively loosely bound phosphate is released from particles in connection with the analysis

My present aquarium is constructed in a way that it contain many organic particles because I love to have many filtrating animals like sponges, some nonphotosynthetic corals and clams. My readings of phosphate with different types of Hanna checkers has been very inconsistent and much higher than expected (compared with ICP and lab analyse of filtrated samples) Therefore I have started to filtrate my samples (0.2 µ) and this give me a consistent reading and inline with other analysis

Sincerely Lasse

 

[ReefHunter006]

This is an interesting thread and it is in some ways opposite to my experiences. I normally get the highest readings in the morning before the lights switch on. This is IMO the most common situation because the production of dissolved PO4 (in the water column) is depended of the bacterial production of orthophosphate (dissolved phosphate) that ongoing 24/7 while the consumption (by corals and algae) only happens when the light is on. My tanks is heavy populated by corals, hence a high photosynthetic activity.

I can see two possible explanations for your experiences.
1. Your food contain free (not organic bound) PO4 that will be Immediately dissolved into orthophosphate (the type of PO4 Hanna checkers reads off). As an example I know that reefroids and some frozen foods can contain this.
2. Tiny particles in the water disrupts Hanna's reading of the sample, alternatively loosely bound phosphate is released from particles in connection with the analysis

My present aquarium is constructed in a way that it contain many organic particles because I love to have many filtrating animals like sponges, some nonphotosynthetic corals and clams. My readings of phosphate with different types of Hanna checkers has been very inconsistent and much higher than expected (compared with ICP and lab analyse of filtrated samples) Therefore I have started to filtrate my samples (0.2 µ) and this give me a consistent reading and inline with other analysis

Sincerely Lasse

Interesting. Any suggestions on where I could purchase the material needed to filter the water. I would love to re do this with that in mind.

I switched from recording on my apex app. But these readings are pretty consistent and show the rises after feedings like benepets(which has yeast).

maybe something interesting worth noting is that certain foods did increase phosphate while others never seemed to impact my readings short term.

I never got a short term increase in PO4 after feeding the following:

Brightwell micro foods
Frozen cubes like cyclopods

Foods that increased PO4 immediately

benepets/reef roids
Reef nutrition phyto feast oyster feast roe and rotifeast
pellets

I looked at multiple feedings where I took tests before feeding, an hour after, 3 hours after then 24.

Benepets powdered food (similiar to reef roids and does contain ash+yeast) looked like this:

Amount of food 1/16 tsp in 100 gallons

po4 before : .06
PO4 1 hour after feeding: .32
PO4 3 hours after feeding .25
PO4 24ish hours after feeding:.1

 

[Lasse]

Not this brand but similar 0.2 µ disc filter

https://www.sigmaaldrich.com/SE/en/products/filtration/laboratory-syringe-filters/syringe-filters

Sincerely Lasse

 

[Lasse]

I know that reef roids addi orthophosphate by itself

Sincerely Lasse

 

[Randy Holmes-Farley Verified Community Expert]

I do know that if PO4 swings are a stressor event for SPS then I would investigate PO4 closely by testing at more regular intervals on the short term to understand the foods impact.

Hour to hour swings may be no stressor at all, and may be true in nature as well.

Day to day or week to week changes are potentially a bigger concern (IMO).

 

[Lasse]

Hour to hour swings may be no stressor at all, and may be true in nature as well.

For a long time - I run my system with a daily swing above 1 dKH and did not see any large problems with my stony corals. However - it was the ones adapted to my aquarium and not the more sensitive of the acropora family. however the value at xx:xx was nearly the same day after day.

Sincerely Lasse