Hi - In the thread about Bolus dosing I have done some tests on my own aquaria in order to understand the behaviour of the alkalinity in my aquarium. As I did test after test - it has grown and IMO does not fit in that thread any more. I decided to start a thread just about these tests and starts with the result I already shown in the other thread
I will fill up with more result. I have get some contradicting result about night consumption when I slowly rise the KH during 3 days but I will let the system work around 9 in dKH for some days
Sincerely Lasse
I Use Triton core 7 3a+b as my alkalinity part. As I understand it - its mainly Na₂CO₃ and lately (before I saw this thread) I have ask myself if there is any delay in dose and showing a result. I use a GHL KH director in adjusting mode, 6 analysis a day. I also have two different base lines for the dose. Between 12:25 and 20:25 base dose is 2,5 ml (3a+b)/30 minutes and between 20:25 and 12:25 it is 0.7 ml/60 min. It means that during my active photoperiod - I dose more than 7 times more than during the darker period. Last 24 hours I dose totally 49,9 ml Core 7 3a+b with only 7.4 ml during dark period - it means 15 % at light intensity below 60% (ramp 2 hours) and 85% at light intensity above 60 % Seen in light on - light of - it was around 14 % alk dos during light off
12/7 it was a total dose of 64,5 ml and even here app 15 % during light off
Nominal value 7.8
My alk during the last week looks like this - the staples are the doses, The blue shows a delayed reaction to dose. Its not always that way but to often in order to total ignore it. The accuracy of the KH director is ± 0.2 dKH this can explain a little - but I have seen it too often to completely ignore it
I do not really understand this but for sure - in my aquarium around 15 % of the alkalinity consumption is in the dark - the rest when my light is on!
My light regime starts 10:00 and stops 22:00. It looks like this
At least for my aquarium according to pH dropp - if my skimmer stops - as in this case around 08:00 - I discover it ar 11:00 - pH responded directly
is this really true? For me and my aquarium - its the total opposite. And my CO2 inside seldom climb over 1000 ppm. Yes it is depended on CO2 in the water but in all case I have seen it is always the opposite. High CO2 in air and water depress the pH - not rise it
Sincerely Lasse
PH 12/7 compared with alk dose. Note the sawtoothing of the curve during the day and the connection of the teeth with the dosage
Sincerely Lasse
The mixing time in my system is around 10 minutes. 300 L DT. Return pump around 1800 L/H. Internal wavemakers - around 40 000L/H. PH meter in the sump measuring water from the DT. KH director intake in the DT. The graph show how fast a pH rise (from the dosed alk (Na₂CO₃)
Maybe this show what I mean better. Nominal value 7.8
I have thought of two things in the past - keep the pH stable around 8.15 with help of a pH managed CO2 injection system and the one you suggest. But my problem is that I have a high bio load system with a lot of organic and hence a lot of bacteria producing CO2 during night. I do not want to dose kalk but I have thought of NaOH. I can make a system there I dose NaOH up to a given pH during night. However - I would also affect alk this way. My system is build on an automatic rise or decrease of the alk dose from Core7 3a+b (I suspect it is Na2CO3) I have a reversed refugium but its not large enough to consume all CO2 produced.
Any ideas how to rise night pH?
I could test with dosing all Core7 2a+b during night too (and nothing during daytime) but the result would be a higher alk in the morning and the alk would vary around 1-2 dKH a day
Sincerely Lasse
Should also mention that I since February have use a daily tempswing - mimicking real watertemperatures (-2 degree C) in Sulawesi-
Highest daily temp at 16:00 - lowest at 04:00
Sincerely Lasse
If I understand you right - my very small changes can be an effect of the method in use? Could be that way - but should not the effect be the opposite if my small changes is pH/CO2 depended? Below - it is a typical pH swing curve for my aquarium.
I understand your standpoint that there is no way to explain this (a possible delay between dose and reading) with help of pure chemistry but could it be a biological way to explain this? However - its only an observation in a rather special aquarium and it could be an artefact as you pointed out
Reading or hear things like this in a discussion where it does not matter make me always want to play this on my record player. This time I played it 5 times
Sincerely Lasse
Thank you for the reopening. I start an experiment yesterday in order to clarify if I can claim a "delay" as my measurements indicate before. I let my KH increase from 7.6 to 8.6 and after that just switch of my dosing. Last dosing was 21:00 yesterday. My KH has decline with 0.6 till now (15:41). -0.3 dKH during the first 15 hours and -0.3 last three hours.
When I rise my dKH - there was no sign of any delay in my system - it rise as should based on the doses.
I´ll comeback with more information later on
Sincerely Lasse
You can never be truly happy - thought that I should be able to report how my system behave during 36 hours without any dosing and get a snapshot of my system's alkalinity needs during this time. Unfortunately I had to change the titration fluid at 9:30pm last night (7/17). since I make it myself, such a change usually involves an adjustment of the displayed value. so this time again. Although manual sampling confirms what the automatic shows, the measurements after 21:00 are not useful, But I have 24 hours of value and it indicates the following:
Between 16/7 at 21:00 and 21:00 on 17/7 my system consumed 1.2 in dKH. This is equal to 21.4 mg/L as CaCO3 (limestone). My water volume is 300 L => total consumption of 6.42 g CaCO3. If my not calcification consumption of alkalinity is around 10% - my system produced around 5,8 g CaCO3 (new limestone) during yesterday.
But the test also indicate when this calcification took place. Between 20240716 21:43 and 20240717 12:43 (15 hours) - the consumption was 0.3 dKH or 25 % of the whole consumption. It means a rate of 0.02 dKH/Hour. Between 20240717 12:43 and 20240717 21:43 (9 hours) - the consumption was 0.9 dKH or a rate of 0.1 dKH/Hour. This indicate that at least in my system and just this day - my calcification rate was around 5 time higher during daytime compared with nighttime
pH curve during this time. Note - the dip in the blue marks is caused by injection of a precipitant for phosphate that always happens 03:14
Interesting is that my daily pH peak normally (with dosing) is around 8.3 but this day (17/7) without dosing it was 8.2. However the lowest reading today was 8.03 - normal daily lowest readings use to be around 8.03 - 8.07. However - there was dosing taking place this night.
Experiment - the blue marking
The results is interesting and I hope I can redo the experiment in the near future.
Sincerely Lasse
Yep
Have fixed the problem. Light was on 65 % when the doses got in
I miss that......
Sincerely Lasse
I start to post in this thread because of the discussion of a "delayed" alkalinity rise when dosing, I had some indications of that in my system - indications that was hard to explain with normal dose - response theory. To test that I dosed up to 8.6 dKH and just stop dosing. The response was as you see in post #919 rather direct - no delay. I thought that it was the end of my doubts - but you can seldom be glad for a long period in this hobby.
When I of mistake did a "Bold bolus dosing" my dKH keep rising for 2 hours after last dose. My pH rise but start to decrease directly after last dose. The pH probe is placed downstream the intake to my KH director, hence Its not an effect of bad water mixing. But I do not have any explanations.....
I will continue with no alkalinity dosing during the night and tomorrow morning at least
Sincerely Lasse
Nope - as you can see it answer to the first doses and pH rise 0.11, 0.1 and 0.09 directly. However - the accuracy is around 0.2 dKH.
Sincerely Lasse
I have found 1 explanation to the curve - something important that can explain most of the confusion. If you look at the graph - the reported dKH (in blue) have the timestamp when the analyse was finished - not when the sample was taken! The sample was taken 12:15 - 15 minutes BEFORE the last addition (in red) That explain most of the "delay" - It was an artefakt. I will probably only make 2 doses today.
I follow up these measurements with two manual methods too - Hanna alk and Salifert
It ended up with I maybe not know my equipment very well.....
Sincerely Lasse
Here is the result for the last two days. As normal with experiments - it leaves you with more questions than you had before the tests. I decided not to spike today and have a normal dosing up to 8 dKH as first step. The only thing that seems to be proven is that at least in my aquarium - there is no large consumption between 00:36 and 06:36. This is the same for all 3 spike tests I have done. Can this be the background precipitation of CaCO3 in my aquarium (not coral driven) ?
pH during the same period
I plan to rise my dKH slowly to around 8.8 again and once again shout down my doses for 24 hours. I will not spike this time
Sincerely Lasse
I will fill up with more result. I have get some contradicting result about night consumption when I slowly rise the KH during 3 days but I will let the system work around 9 in dKH for some days
Sincerely Lasse
