What is considered a normal NO3 & PO4 daily swing.

[TLO45]

I’m curious what is considered a normal daily swing of phosphates and nitrates?
When reefers state it’s important for stability of nutrients (which I certainly agree with) but when I do daily tests nitrates are pretty steady. However phosphate varies a certain amount. For example: yesterday I tested phosphate at .09. Today it was .19. Nothing abnormal in feeding and taken same time of day.
If this is normal, then what’s the purpose of testing for levels if they vary this much?
When I read about tank overviews reefers stating phosphate numbers it’s a steady number. Is this really true or just a number that people take before the article written?
If I reacted to my daily numbers then I would be removing one day and adding the next.
Can anyone tell me what they do?

 

[Randy Holmes-Farley Verified Community Expert]

I don’t think most folks believe there needs to be stability minute to minute. It is day to day that matters. The values likely fluctuate in relation to feeding and other timed processes.

 

[Dan_P]

I’m curious what is considered a normal daily swing of phosphates and nitrates?
When reefers state it’s important for stability of nutrients (which I certainly agree with) but when I do daily tests nitrates are pretty steady. However phosphate varies a certain amount. For example: yesterday I tested phosphate at .09. Today it was .19. Nothing abnormal in feeding and taken same time of day.
If this is normal, then what’s the purpose of testing for levels if they vary this much?
When I read about tank overviews reefers stating phosphate numbers it’s a steady number. Is this really true or just a number that people take before the article written?
If I reacted to my daily numbers then I would be removing one day and adding the next.
Can anyone tell me what they do?

Quit putting too much stock in reef tank overviews

I am not aware of a study that measures the nitrate and phosphate in an aquarium throughout the day with a method of known precision. Both frequent measurements and known precision are needed to demonstrate how stable is stable. But even when the nitrate concentration stability is measured, if the effect on coral is not studied under controlled conditions, the “so what” question is not addressed. My system has a stable nitrate concentration, so what?

 

[Reefahholic]

Normal daily….

I try to keep my tank from swinging more than .05 ppm P. But typically it’s about .03 ppm. Nitrate no more than like 1-3 ppm daily. Although both can handle more, I feel like the less swing the better. I’ve had pretty good luck like that. Nitrate swings seem to be a little less irritating to the corals.

If dosing I only increase by .02 daily,
or 1 ppm daily unless the tank needs more to stay at target.

 

[TLO45]

So what are people measuring levels with?
I just ran 3 separate tests with Hanna phosphate tester HI 713
This was within a 15 minute window
Test 1. .09
Test 2. .14
Test 3. .11
Obviously this is a wide range in my mind.
How do you trust any of these?
I emailed Hanna about this to see if the actual tester itself would go bad?
They responded that the reagents can expire ( which I already know and replace frequently) but the tester itself does not expire.
So how do you know where the levels are actually at?

 

[Randy Holmes-Farley Verified Community Expert]

So what are people measuring levels with?
I just ran 3 separate tests with Hanna phosphate tester HI 713
This was within a 15 minute window
Test 1. .09
Test 2. .14
Test 3. .11
Obviously this is a wide range in my mind.
How do you trust any of these?
I emailed Hanna about this to see if the actual tester itself would go bad?
They responded that the reagents can expire ( which I already know and replace frequently) but the tester itself does not expire.
So how do you know where the levels are actually at?

All of those are well within the Hanna claimed margin of error of +/- 0.04 ppm.

All of them are also fine.

 

[SliceGolfer]

I don't monitor the swing in N03 or P04. I test to confirm the value is above zero, and within a range of 0.03-0.10 for P04, 3ppm-10ppm N03. If values are trending downward I may dose trisodium phosphate or ammonium bicarbonate accordingly. If high, I usually don't do anything but I will keep an eye on the lowest value as the gap changes. I like to maintain a 100:1 ratio of N to P, or close to it. I find in a day or two, things shift back in line.