Alk spike at night without dosing

djkms · Dec 8, 2021

Hello all,

So I have my trident setup to test the standard 4alk per day and 2CA, 2MG. I don't have a DOS but I do run my programming with virtual outlets using BRS 1.1ml dosers. I don't quite understand my 6am readings honestly. I only dose alkalinity during lights on which is from 9:30am to 9:30pm (this is when the consumption is happening in my system). Every day my alk spikes up roughly .10 to .20 from the 12am to the 6am reading. How is this possible if I don't dose anything during that time? The reason this is an issue is because I have thresholds where I don't dose over a certain number and it usually prevents my dosing from 9:30am until the next test at 12pm and now its playing catch up. I obviously want to stabilize this somehow. Here is my programming for my soda ash container:

Fallback OFF
OSC 030:00/002:30/027:30 Then ON
If ALK < 8.01 Then OFF
If Output AlkLow = ON Then ON
If ALK > 8.05 Then OFF
If Output AlkHigh = ON Then ON
If Output GFOChange = ON Then ON
If ALK > 8.14 Then OFF
If Output TridentTest = ON Then OFF
If pH > 8.30 Then OFF
If Output Acclimate = ON Then OFF
If Time 20:29 to 09:29 Then OFF

AlkLow
OSC 030:00/003:30/026:30 Then ON
If ALK > 8.00 Then OFF

AlkHigh
OSC 030:00/001:30/028:30 Then ON
If ALK < 8.05 Then OFF

And my CA if that helps (runs all day)
Fallback OFF
OSC 010:00/001:15/048:45 Then ON
If CA < 425 Then OFF
If Output CALow = ON Then ON
If Output CALowPlus = ON Then ON
If CA > 430 Then OFF
If Output CAHigh = ON Then ON
If CA > 434 Then OFF
If Output TridentTest = ON Then OFF

So if this is just chemistry any thoughts on a better way to program my outlet to avoid swings? Granted they are small but something has to explain this. I have changed around my CA dosing from all day long to only at night to only during the day and it has not changed anything with my ALK swings. If anything my ALK should be going down at night since nothing is dosed, not up.

Any help or thoughts appreciated!

clown99 · Dec 8, 2021

I don't know how big your system is but in my opinion, the Alk/Ca/Mg numbers are not or should not be programmable as conditional statements. There's also many other factors involved. In my 29g biocube, if I change the dosing +/-1mL, without changing any other parameters (light patterns, flow patterns, etc), I'd wait for 48 hrs to measure and take action if any. I would test at the same time as well.

Borat · Dec 8, 2021

djkms said:
Hello all,

So I have my trident setup to test the standard 4alk per day and 2CA, 2MG. I don't have a DOS but I do run my programming with virtual outlets using BRS 1.1ml dosers. I don't quite understand my 6am readings honestly. I only dose alkalinity during lights on which is from 9:30am to 9:30pm (this is when the consumption is happening in my system). Every day my alk spikes up roughly .10 to .20 from the 12am to the 6am reading. How is this possible if I don't dose anything during that time? The reason this is an issue is because I have thresholds where I don't dose over a certain number and it usually prevents my dosing from 9:30am until the next test at 12pm and now its playing catch up. I obviously want to stabilize this somehow. Here is my programming for my soda ash container:

Fallback OFF
OSC 030:00/002:30/027:30 Then ON
If ALK < 8.01 Then OFF
If Output AlkLow = ON Then ON
If ALK > 8.05 Then OFF
If Output AlkHigh = ON Then ON
If Output GFOChange = ON Then ON
If ALK > 8.14 Then OFF
If Output TridentTest = ON Then OFF
If pH > 8.30 Then OFF
If Output Acclimate = ON Then OFF
If Time 20:29 to 09:29 Then OFF

AlkLow
OSC 030:00/003:30/026:30 Then ON
If ALK > 8.00 Then OFF

AlkHigh
OSC 030:00/001:30/028:30 Then ON
If ALK < 8.05 Then OFF

And my CA if that helps (runs all day)
Fallback OFF
OSC 010:00/001:15/048:45 Then ON
If CA < 425 Then OFF
If Output CALow = ON Then ON
If Output CALowPlus = ON Then ON
If CA > 430 Then OFF
If Output CAHigh = ON Then ON
If CA > 434 Then OFF
If Output TridentTest = ON Then OFF

So if this is just chemistry any thoughts on a better way to program my outlet to avoid swings? Granted they are small but something has to explain this. I have changed around my CA dosing from all day long to only at night to only during the day and it has not changed anything with my ALK swings. If anything my ALK should be going down at night since nothing is dosed, not up.

Any help or thoughts appreciated!

I also observed this phenomenon, usually it's between 3am and 6am readings for me and it's about 0.2DKH as well..

To be honest I stopped thinking about the reasons for this unexpected spike and just monitor readings vs previous day.. As soon as these are stable - I am adding the correct amount of alk..

DrMMI · Dec 8, 2021

Both my tanks do the same thing. I don't dose any alk from 11:30pm - 6:30am, but I notice a rise in the alk every night with the 6am testing on the trident. I started dosing less alk from 6:30pm - 11:30pm and I noticed less of a spike at the 6am testing

djkms · Dec 10, 2021

DrMMI said:
Both my tanks do the same thing. I don't dose any alk from 11:30pm - 6:30am, but I notice a rise in the alk every night with the 6am testing on the trident. I started dosing less alk from 6:30pm - 11:30pm and I noticed less of a spike at the 6am testing

Good strategy. I just implemented the same thing and although my 12am reading is now lower, my 6am reading is better as well which is now about even with my 6pm reading. Thus allowing dosing in the morning.

Still curious why ALK would rise with nothing being dosed from 12am to 6am?

brahm · Jan 10, 2022

I noticed the same thing when I set up the tank with a trident. I have a different dosing schedule at night than I do during the day.

I posted about it a while back. here: https://www.reef2reef.com/threads/w-what-is-everyones-daily-alk-consumption-trends.807885/

I'm going to give @Randy Holmes-Farley suggestion a try starting tonight. I'm setting up a Kalk reactor and my plan is to run it on the reverse schedule of my PH peaks; so starting with where it declines ramping up to max decline and then ramping down to where it starts to taper back up with the lights.

Honestly, I've never paid much mind to PH In the past, however where I live now I have a swamp cooler that runs all summer and windows are open in the spring and fall so I had great PH. Then when winter hit, I noticed my tank was slowly declining wouldn't say it was looking bad, or things weren't growing but something didn't seem right. At which point I recalibrated my PH probe and realized that I was nowhere near where I thought I was, so I re-hooked up my skimmer to the outside line which bumped the Ph from a high of sub 8 flat or so, to a low of 8.05 and a high of 8.26.

Numbers aside, within a day everything perked back up my anemones started looking as good as they did all summer, polyps on my sps the same, that was enough proof for me so I ordered a kalk reactor (showing up today) and here we are.

As to what that has to do with alk at nite; well I'm hoping that by running kalk on a reverse schedule I can level out my ph which will reduce the DKH swings. I also plan on shutting off the calcium reactor at nite as I'll be getting some supplementation to alk/calc from the Kalk. I am however worried that I may end up making ALK swings worse though so I will be tuning it through a DOS / Apex vs ATO.

Randy Holmes-Farley · Jan 10, 2022

I could speculate on a number of reasons, but I have no idea if they are the explanation.

1. Since ammonia conversion to nitrate consumes alk and nitrate consumption by organisms adds that alk back, even with stable nitrate, if the production and consumption of nitrate do not happen at the same time, you may see rises when nitrate consumption dominates, and alk drops when nitrification of ammonia dominates.

2. Low enough pH at night, especially in near surface regions of sand and rock where pH may be even lower, may be when some calcium carbonate dissolves, which would lead to an alk rise at that time. Long term reefers do notice a decline in sand levels over months to years, so it is dissolving at some time, and night makes the most sense.

3. Some organisms consume sand, and may dissolve some of it in their GI tract. if these are more active at night, alk would rise. Sea cucumbers do this:

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fryman · Jan 11, 2022

That's interesting.

I actually dose kalk at night in an attempt to stabalize pH, and I also get peak alk readings at 6AM, about 0.3 dkh higher than lowest point at midnight. But I dose between midnight and noon (lights out) so I figured that was why. I don't have a clue why alk would peak at 6am when you aren't dosing then.

brahm · Jan 15, 2022

woah! It worked (so far). I’m a few evening in now and while I know that’s not a lot of data I am fondly surprised. My alk isn’t spiking at night anymore. However my ph is both going up and reducing the swings.

I set the Kalk reactor up on a doser to match when my ph was starting to drop and turn off when it was starting to raise.

I then turned off my doser for my calcium reactor at the same time unless my alk is below a threshold.

and now my ph is higher and the swings are getting smaller and my alk is staying within the same tolerance. (There is some funk in my data as I’ve been increasing the kalk to find a balance and I had an apex issues I had to sort) but it’s looking promising hopefully after a month or so of logs I’ll be able to fine tune things.

I am seeing more swings in alk overall though but it seems to not be over night but related to larger usage during peak periods that I’m going to have to adjust for. Result of higher ph? @Randy Holmes-Farley ?

Randy Holmes-Farley · Jan 16, 2022

brahm said:
I am seeing more swings in alk overall though but it seems to not be over night but related to larger usage during peak periods that I’m going to have to adjust for. Result of higher ph? @Randy Holmes-Farley ?

Folks who measure alk continuously notice that most alk is consumed during the day.

It is not clear to me whether that is because:

1. corals calcify faster at higher pH
2. There is a direct effect of photosynthesis on calcification rate in corals
3. Some combination of the two effects
plus, abiotic precipitation will be higher at higher pH.

I'm still waiting for the day when someone measures alk 24/7 in a tank with a pH peak during the night due to some sort of pH controlling mechanism. It's a hard experiment to do.

brahm · Jan 16, 2022

Randy Holmes-Farley said:
Folks who measure alk continuously notice that most alk is consumed during the day.

It is not clear to me whether that is because:

1. corals calcify faster at higher pH
2. There is a direct effect of photosynthesis on calcification rate in corals
3. Some combination of the two effects
plus, abiotic precipitation will be higher at higher pH.

I'm still waiting for the day when someone measures alk 24/7 in a tank with a pH peak during the night due to some sort of pH controlling mechanism. It's a hard experiment to do.

hmm, I would think maybe that is something someone doing kalk slurry could pull off as you can peak that easier with less, although you would then also have to do the inverse and add C02 or something in the day to reduce the ph otherwise it would build on top of each other.

In ref to my situation, I am starting to see a trend of a .2 jump in ALK over the course of the evening which is from running kalk at night without the Calcium Reactor. However prior I was seeing around up to .2 swing at night with the calcium reactor running prior to kalk so I'm not sure if it's going to be a consistent thing just yet.

What I am also seeing however is an increased amount of consumption during peak hours. If this trend continues I can do one of two things

1) Increase the calcium reactors dosage to meet the demand during peak times. Level it out so I'm not swinging down, and then based on how things react possibly adjust the Kalk

2) or add an additional dose for the kalk reactor so that is also running during peak hours.

The first option in theory would result in a more stable ph, the second option would give me a higher overall ph as I would no longer be reverse dosing, but essentially at that point kalk for most of the day. I am not sure which would be more beneficial; more so now that my ph seems to be settling in at about 8.2 - 8.34

I may also bump up the amount of ALK tests for more granular data.

Randy Holmes-Farley · Jan 17, 2022

brahm said:
hmm, I would think maybe that is something someone doing kalk slurry could pull off as you can peak that easier with less, although you would then also have to do the inverse and add C02 or something in the day to reduce the ph otherwise it would build on top of each other.

One can imagine how to keep alk stable 24/7 and have pH higher at night, but it takes quite substantial effort, possibly involving either a lot of aeration and high control and ability to change CO2 levels in the air, or something similar.

Just dosing high pH additives at night has not typically been shown to be able to reverse the pH cycle, and even that would need other additions during the day to stabilize alk 24/7.

Borat · Jan 17, 2022

Randy Holmes-Farley said:
One can imagine how to keep alk stable 24/7 and have pH higher at night, but it takes quite substantial effort, possibly involving either a lot of aeration and high control and ability to change CO2 levels in the air, or something similar.

Just dosing high pH additives at night has not typically been shown to be able to reverse the pH cycle, and even that would need other additions during the day to stabilize alk 24/7.

Agree - a bit of a pointless efforts to do that. Just check every morning that the Alk level is the same as the morning before,,

I started to get Alk stability and reduced testing to 3 times a day - morning, mid-day and evening.. Sometimes when you test too often and chase stability - you end up introducing instability as the accuracy of DKH measuring device is at best 0,1DKH anyway,,,

brahm · Jan 17, 2022

Borat said:
Agree - a bit of a pointless efforts to do that. Just check every morning that the Alk level is the same as the morning before,,

I started to get Alk stability and reduced testing to 3 times a day - morning, mid-day and evening.. Sometimes when you test too often and chase stability - you end up introducing instability as the accuracy of DKH measuring device is at best 0,1DKH anyway,,,

true there is an art to it, dont want to spin into a hole. But more data isnt bad if you know what to do with it. managed to get myself down to around a < .1 daily swing which I’d say is pretty solid. Have to look at what its doing in relatonship to everything else going on.