Discussion in 'Reef Chemistry by Randy Holmes-Farley' started by LetItReef, Feb 7, 2018.
Is there a best time to test parameters- morning, afternoon or at night and why? Thanks!
i dont think there is any best time of the day to test, i recommend consistency in testing about the same time everyday or every time you test.
I work over night and come home around 4-5am and i test regularly about that time.
This is a good topic to discuss ...
The whole nature is dominated by rhythms, some governed by the sun, others by the moon and still others by the internal regulation of each organism, according to what complexity and according to which metabolism. All these cyclic rhythms are called the circadian cycle.
If it were possible to measure all the variations of an ecosystem from instant to instant 24/7 hours and days, we would see that each parameter establishes a curve and that each curve tends to be "constant" over time, establishing the cycle.
So that we can point to a point in this circadian curve, establishing a target to be reached, it is important to determine the instant "t" in which the point appears in the curve during the 24 hours, otherwise we will be lost.
From this determination, and for comparison / monitoring purposes, the measurements should always be made at the same time "t" or very close, and other variations occurring in the measurement environment, such as temperature, salinity, pH, potential redox , lighting ... all able to change, little or much, each of the parameters measured.
Choosing test time, it is good practice always performed at the same time, or close, so that we can get a good idea of the variation of that particular parameter over the course of days.
That's my opinion.
Depending on systems - some parameters can alter during the light regime. Known altering parameters is pH, PO4, NO3, KH, O2, CO2 and NH4/NH3
In a reef system (lot of corals) without a reversed light regime fuge pH and O2 will be lowest just before light coming on and highest when max light is going down. PO4, NO3, KH, NH3/NH4 and CO2 will be the opposite.
It wise as Dr.Reef stated to test at the same time. However - to test before light coming on and just when light leave max intensity can give some important information about the system
The basic parameters (alk, Ca, magnesium) will not naturally cycle day to night so in that sense, time itself does not matter. But when you measure in relation to when you dose (whether that means once a day, many times, continuously, etc.) can be important and should be consistent.
pH and O2 and things related to them (e.g., ORP) are the main ones that change with the light cycle.
Others may change with the feeding cycle (ammonia, etc.).
What about in relation to a water change? Before or after?
I usually test right before my water change to see the lowest levels to make adjustment to dosing or the the actual water change water if need be.
That's good to know. I've been doing it the day after water changes.
I think it was Jonas Roman that reported a cycle of of alk (KH) during 24 hours or at least more consumption during light periods - I can be wrong with that.
However - at least in my systems - with sand and type of DSB - there is a bacterial production of NH4 and PO4 that is constant during 24 hours but during light time its consumed by the photosynthesis in a rate that the production is lower than the consumption. PO4 can vary from 0.1 down to nearly zero depending on time I take my tests.
I have done this tests with high end Spectrophotometers for PO4 – so for that parameter I´m total sure. In systems with reversed photoperiod for the fuge – its normally not very much of variation.
IMO - the bacterial production of NH4, PO4 and CO2 is at least in my system higher than the production from the fish due to a natural system there algae and animals will live an die, hence produce dead organic matter for the bacteria to breakdown. In system with adding organic carbon - the production from bacteria is much higher.
I test at the same time of the day.
If I make an adjustment, I retest in 24 hours.
I usually test 12hr after dosing.
Thanks everyone! I do my basic params test in the morning 8- 8:30.
Yes, several folks have shown demand is mostly during the day. But it is not a natural cycle, just a downward trend unless you dose in a way that causes a cycle, such as continuous dosing with demand mostly during the day causing a “cycle”.
So many variables for choosing the correct time but I think this is the most important thing to keep in mind.
And if dosing manually or doing water changes, give the tank water at least a couple hours to re-mix properly.
Maybe I mispronounced, but did not say that "all" parameters should be measured at the same time ...
What I meant is that each parameter should always be measured at the same point in the curve, if it is cyclic, so that we can be able to evaluate its actual fluctuations. Parameters that fluctuate throughout the day, if measured in random hours will have random result, difficult to fit in a curve of normality.
ORP and pH are good examples of this, as are all those who depend on the lighting cycle.
I didn't say you did. I was agreeing with you.
In general, test at the same time. Whatever test that may be. If you tested alk mid afternoon yesterday, test alk mid afternoon today.
I do the same thing when weighing myself! Same exact time in the morning.
That's it, exactly!
there are many variables even with picking 1 consistent time of the day. As per my last statement (post #2 on this thread) testing everyday at same time or close should be the best practice but also know your dosing arrangement water changes time etc. for example i test my tank every morning after work at 5am but it wouldnt be meaningful if my tank is dosing alk at 430am or 445am or there are water changes performed at 4am etc. All those things will not tell you true parameters of your tank. so choose a time that you can do testing everytime about the same time any day you want with the knowledge that there are no dosing or water changes or any other things that can alter your reading. let all those things settle at least 2-4 hrs before testing. i hope it all sound clear.
There is no better time than any other, there is only consistency. I would strongly recommend dosing *after* testing, though on a sufficiently large (400+ gal, total volume), established system you can get away with this. But only if you do this consistently.
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