Integrating the Alkatronic, Apex and Dos for stable alkalinity AND pH.

[Reefinmike]

And I just ordered that CO2 sensor from ebay. Its coming from NC, so hopefully it won’t take too long to get here to florida. I also looked through the manual for it and in addition to the 0-5V output that would work with the ASM it looks like it also has a relay output that can be set to trip at a specific CO2 level, so I’m thinking I might just be able to use that with a port on a breakout box.

Interesting findings! it's pretty wild how much things we do unconsciously(breathing) can affect our reefs. I've heard neptune urban legends about a man that caught his wife cheating via his pH graph... I'm starting to believe how plausible that can be. I'd love to see you have great success with the scrubber. I've been "against" them from the beginning; mostly because of things that make it dangerous for the average user. saturating the media could be disasterous so you have to set it up *JUST* right. If the media suddenly expires while you're on away, alk demand could drop drastically and skyrocket alk without dosing control automation. From what I've seen, doesn't seem cheap or sustainable. Don't get me wrong, I have absolutely no doubt you have the knowledge and tools to use a scrubber safely. It's something I'd definitely consider adding once you perfect your methods, specifically in tandem with Lye dosing. I'm pretty sure you mentioned it somewhere but how is your air intake bypass with solenoid(or pinch valve?) plumbed? Do you toggle between pulling air through the scrubber and simply bypass the scrubber recirculating only the air within the skimmer body? or do you recirculate and periodically pull room air? It seems that you'd burn through media fast if you pulled room air. it's like ticking in the wind- Scrubbing co2 from the water only to reintroduce it in the system when pH reaches your max setpoint.

Admittedly, I don't know all the chemistry behind how acids interact with water so I may be talking out of my butt here. My understanding is that CO2 bonds with a water molecule to form carbonic acid or H2CO3. pH is a negative logarithmic scale of free hydrogen ions in the water meaning that water with a low pH has significantly more free H Ions than water with a "normal" pH. Adding soda ash(Na2CO3) raises pH because the carbonate wants to pull in a H ion to create bicarbonate(HCO3) which makes up ~97% of reef alkalinity. chemical reactions work in both directions and carbonic acid(H2CO3) isn't all that different than bicarbonate(HCO3)... Does carbonic acid disassociate into bicarbonate when the pH(concentration of H ions) presents the proper conditions? Do corals in our oceans get their alkalinity through atmospheric CO2? being a photosynthetic organism I'd think coral gets it's carbon from the same initial source plants use. If this logic is true, does that mean a CO2 scrubber is just removing potential alkalinity from the system? that would explain the sudden "increase in alk demand" that people see from a scrubber.

Lye adds a hydroxide(OH) ion to the system and pulls in a free H Ion to create H20. the reduced free hydrogen concentration means a higher pH and that "pesky" carbonic acid disassociates from H2CO3 to HCO3 or bicarbonate alkalinity. we're using hydroxide to turn an acid into "alkalinity"- the reef's buffering system against acid. If you're following the word vomit logic typed above, you may see why I feel CO2 scrubbing is a backwards way of controlling pH. You're removing something then adding more of another thing to correct the levels. On the other hand, CO2 scrubbing doesn't add that extra sodium ion... but you also add sodium when you dose more soda ash or bicarb to fix that "sudden increase in demand"


Sorry for the rambling. I hope I don't sound argumentative here... I'm genuinely curious about which methodology(scrub vs dose) is *right*. Both certainly seem to work. I think it all boils down to overall cost in the end.

 

[Brett S]

It was definitely interesting to read your description of how alkalinity and pH are tied together. I read it several times and still probably only got about 50% of what you’re saying, but I’ll read it a few more times later. Chemistry definitely wasn’t one of my strong subjects in school

I am really just getting started with the whole C02 scrubbing thing, and like you said, there really are a lot of downsides. I had been resisting it for quite some time, but at this point I think it’s really my only option for controlling the big pH dips that I’m seeing when there are additional people in the house. I don’t want to rely on it all of the time, but for the few days a month that I need it, I think it will be acceptable to use to help keep my pH (and with that, my alkalinity demand) stable.

I guess the good news is that CO2 scrubbing is something that I only need when there are a lot of people in the house, so when I’m away it won’t be in use and I won’t need to worry about the media being exhausted unexpectedly without being able to change it.

I definitely still have a lot of experimenting to do to try to figure out the best way to set it up, but right now I’m just pulling room air through the scrubber (Well, technically it’s sump air, but I don’t think the sump air is significantly different than the room air in terms of CO2 levels).

I had considered trying to recirculate the air, and I probably will at some point, but the reason I didn’t do that right now is because I’ve had times where my skimmer produces so much foam that it fills the cup entirely and starts coming out the vent holes. This happens frequently enough (maybe once every month or two) that I was concerned about the system trying to suck foam through the CO2 media and making a mess. I’ll probably need to put a moisture trap on the line when I try to set up the system to recirculate the air.

My guests will be leaving today and I won’t have people here for another two weeks, so maybe I’ll have a chance to set up recirculation and test it then. In the mean time I should be able to take the CO2 scrubber offline.

 

[Brett S]

I‘ve been spending a bit more time thinking about this and I’ve decided that the logic I have been using for switching between the soda ash and the lye is completely wrong.

I don’t want to switch to lye only when the pH dips below a certain number. Instead I want to switch to lye as soon as the pH starts trending down in the night. And in the morning I don’t want to keep dosing lye until the pH rises over a certain number, but I want to stop dosing lye and switch to soda ash as soon as the pH starts trending up.

Doing so should minimize the peaks and valleys even more as the lye should help boost the pH during the entire time that it is trending down and at the same time, as the pH is trending up I won’t be dosing any lye, which would cause it to jump up even faster.

Unfortunately, I don’t believe that the apex is capable of determining if the pH is trending down or trending up. However, as I studied my pH graph I discovered that rises and falls happen at nearly the same time every day. So I added a new pH_High virtual outlet and I set up another virtual outlet called Dose_Control that looks like this:

Dose_Control:
Set OFF
If Time 21:30 to 10:30 Then ON
If Output pH_High = ON Then OFF
If Output pH_Low = ON Then ON

I configured the pH_High outlet to come on when the pH is over 8.19 and the pH_Low outlet to come on when the pH is below 8.11.

I then configured the system to dose lye when Dose_Control is ON, and to dose soda ash when Dose_Control is OFF.

From looking at my graph I discovered that my pH hits it’s peak and starts falling at 21:30. So it is at this point that the system will start dosing lye. However, if the pH is above 8.19 it will continue dosing soda ash until the pH drops to 8.19 or below. This way if something happens and it takes a little longer than normal for the pH to start dropping I’m not just blindly dosing lye and causing it to go up.

And likewise, I discovered that at 10:30 my pH is starting to rise after hitting it’s low for the day. So it is at this point that the system will switch to soda ash. Again, there is another control in there that will have it keep dosing lye if the pH is below 8.11, in case the pH doesn’t start rising exactly when I expect it to.

Theoretically this should keep the pH between 8.1 and 8.2, however, I will need to see exactly how things behave after it’s been running for a few days and make some adjustments to the numbers, if necessary.

I also do want to attempt to increase the pH a bit more over time, maybe aiming for 8.2-8.3 or even 8.25-8.35, but again, I want to make those changes slowly, so I’m going to start with this.

 

[Brett S]

My motorized ball valve arrived today and I was able to connect it to one of the 24V accessory ports on my apex, so now the apex can enable or disable the CO2 scrubber.

My CO2 monitor shipped today and will hopefully be here in a few days. I think I’m going to try to just connect it with the relay control to one of my breakout boxes. If that works, then I won’t need to worry about getting an ASM module.

 

[Reefinmike]

I‘ve been spending a bit more time thinking about this and I’ve decided that the logic I have been using for switching between the soda ash and the lye is completely wrong.

I don’t want to switch to lye only when the pH dips below a certain number. Instead I want to switch to lye as soon as the pH starts trending down in the night. And in the morning I don’t want to keep dosing lye until the pH rises over a certain number, but I want to stop dosing lye and switch to soda ash as soon as the pH starts trending up.

Doing so should minimize the peaks and valleys even more as the lye should help boost the pH during the entire time that it is trending down and at the same time, as the pH is trending up I won’t be dosing any lye, which would cause it to jump up even faster.

Unfortunately, I don’t believe that the apex is capable of determining if the pH is trending down or trending up. However, as I studied my pH graph I discovered that rises and falls happen at nearly the same time every day. So I added a new pH_High virtual outlet and I set up another virtual outlet called Dose_Control that looks like this:

Dose_Control:
Set OFF
If Time 21:30 to 10:30 Then ON
If Output pH_High = ON Then OFF
If Output pH_Low = ON Then ON

I configured the pH_High outlet to come on when the pH is over 8.19 and the pH_Low outlet to come on when the pH is below 8.11.

I then configured the system to dose lye when Dose_Control is ON, and to dose soda ash when Dose_Control is OFF.

From looking at my graph I discovered that my pH hits it’s peak and starts falling at 21:30. So it is at this point that the system will start dosing lye. However, if the pH is above 8.19 it will continue dosing soda ash until the pH drops to 8.19 or below. This way if something happens and it takes a little longer than normal for the pH to start dropping I’m not just blindly dosing lye and causing it to go up.

And likewise, I discovered that at 10:30 my pH is starting to rise after hitting it’s low for the day. So it is at this point that the system will switch to soda ash. Again, there is another control in there that will have it keep dosing lye if the pH is below 8.11, in case the pH doesn’t start rising exactly when I expect it to.

Theoretically this should keep the pH between 8.1 and 8.2, however, I will need to see exactly how things behave after it’s been running for a few days and make some adjustments to the numbers, if necessary.

I also do want to attempt to increase the pH a bit more over time, maybe aiming for 8.2-8.3 or even 8.25-8.35, but again, I want to make those changes slowly, so I’m going to start with this.

I bet you could do something really fancy based on your lighting wattage. perhaps even by referencing the 0-10v if you're using kessils.

A chemist friend confirmed my logic basically stating that the ocean gets it's carbonate "alkalinity" from atmospheric co2. I've attached his replies; He's better at explaining it than I.

What is the "Carbonic acid-bicarbonate" buffer system? | Socratic

It's a buffer system that consists of a weak acid and its conjugate base. The carbonic acid - bicarbonate buffer system consists of carbonic acid, a weak acid, and the bicarbonate anion, its conjugate base. The important thing to realize here is that carbonic acid, H_2CO_3, is actually formed...

socratic.org

1. Yes, our ambient CO2 combines with H2O to make carbonic acid (H2CO3).
2. When you dose hydroxide, it strips a hydrogen from that to push the pH back up due to the now-bound proton (hydrogen nucleus). This means your water + CO2 + OH gives you water and bicarbonate.
3. Bicarbonate is only used for skeletal growth when necessary, because the extra hydrogen in bicarbonate (HCO3) must be shed through the coral tissue when laying down the calcium carbonate (CaCO3).
4. As more hydroxide enters the system, with most carbonic acid already converted to bicarbonate, you'll get the hydroxide stripping the hydrogen from bicarbonate to leave you with simple carbonate, the exact anion needed for skeletal growth.
5. If you dose more hydroxide when most bicarbonate (and carbonic acid) are already converted to carbonate, you get a horrid pH spike and terrible things happen...Don't do that.
So Mike's got great chemistry backing him up for the theory and reality of this. But he will be as fast as anyone to caution you to have redundancies controlling this. His system is monitoring pH with redundant probes, when the pH goes over a threshold (I think 8.25 in his code IIRC), the dosing switches to dose (bi?)carbonate instead of hydroxide, otherwise the pH can swing wildly when the carbonic acid concentration gets too low. I think he has all dosing shut off if the pH goes really high (8.5, maybe?)

Mike McName-
the sodium isn't going to be different either way. At least presuming your alkalinity dose is coming with a normal sodium chloride based 2 (or 3) part dosing regimen and the hydroxide is with sodium. Obviously if you were dosing kalkwasser for hydroxide or dosing potassium hydroxide, that changes the sodium conversation.
By dosing hydroxide, you're essentially leveraging some of the dissolved CO2. To dissolve in water, the CO2 has to pickup protons and become carbonic acid. If you move equilibrium by using a CO2 scrubber or opening a window, or running outside air for the skimmer intake, then some of that carbonic acid will convert back and offgas some CO2, thus moving your pH up.
By dosing hydroxide, you're basically robbing the dissolved CO2 (carbonic acid) of its proton (because the hydroxide sort of steals it), so you have a poor version of alkalinity (bicarb). Further hydroxide dosing robs another proton from the bicarb, leaving you with the more bioavailable alkalinity (carbonate).
I don't think it's really fair to say by running a scrubber that you're removing alkalinity. There's two things to think of chemically here.
1. alkalinity is not, technically, the thing coral needs. alkalinity is really just a measurement of buffering capacity (fancy word for the water's ability to resist change in pH). We usually think of alkalinity as the thing corals need because normally the vast majority of the buffering capacity is coming from carbonates. But there are lots of other things you can dissolve into the water that provides great buffering capacity...but that means your alkalinity test will give a false result because it'll show all the buffering capacity, not just the carbonates. Carbonic acid has a pH of 4.63, so for the purpose of our reef tanks, it's working against our desired buffering capacity (pH 8.13 has about 3126 as many protons per liter as a saturated solution of carbonic acid).
So no, carbonic acid really isn't adding alkalinity to the water, and removing it isn't removing alkalinity. You *feel* that way, because you're dosing something that causes a very convenient change to the carbonic acid that converts it into a useful buffer for our tank...thus raising the pH...because you added freaking lye to the water

2. carbonate is the thing corals need to grow, they can't use bicarbonate without stripping the extra proton off (which they can do, but that just lowers the pH of the water, especially in their tissue, which makes it even harder to do that with the next one because they're fighting against equilibrium). Carbonic acid doesn't help them grow unless the pH moves up (which means the carbonic acid converts to (bi)carbonate.
So again, no...carbonic acid is definitely not useful to the coral's growth, and removing it isn't removing something it can use. You *feel* like it is because you're dosing something that converts it into carbonate that the coral can use.
So a CO2 scrubber is preventing carbonic acid, which holds the pH down, and the coral can't use. Then you have to dose the alkalinity like normal, not really interesting here, but you don't have soda lime hanging out waiting to get sucked into the water and crashing your tank (yes, I looked it up...it's soda lime...eek)
Bye dosing lye, you're not actually adding alkalinity. You're dosing something that reacts with dissolved CO2 to essentially *create* alkalinity (in the form of (bi)carbonate) in the water and leaves byproducts of H2O and sodium (the later is also a byproduct of dosing normal two part). So if you like dosing part C with your 2-part and are switching to a hydroxide-based alkalinity, you ought to still be adding part C, it's no different from an ionic imbalance perspective.
The debate is basically if you prevent the CO2 from getting dissolved (CO2 scrubber) and dose 2-part, or you let the CO2 get dissolved and convert it to carbonate (by dosing hydroxide-based 2-part). Either should work fine with a major caution for each:
CO2 scrubbing: don't you dare *ever* let that media touch your tank water. That stuff is NASTY and will spike your pH in a hurry. Also, if you let it get exhausted and don't notice, your pH will drop (assuming it was helping in the first place) and your alkalinity consumption will fall because corals can't use the alkalinity as efficiently as they could before. if you don't notice fast enough, you could end up with spiking calcium and alk.
hydroxide dosing: At some point, your corals *might* consume more carbonate per day than the amount of CO2 that's dissolved in the water. Once that happens, there's a shortage of carbonic acid to convert into carbonates and the hydroxide is left free in the water. That will start raising the pH in a serious hurry...could be real bad. I wouldn't do this with hydroxide as my only dosing option (though it's what all those kalk-only people do...). I'd do it like
Mike
, with a very careful eye on pH with automation to switch to a regular (bi)carbonate dose when pH starts to go above 8.2(ish). That way when the hydroxide dosing is faster than the carbon dissolving, the pH won't spike (which btw, would also mean less actual carbonate for the coral to grow...hence wanting to dose regular alkalinity during high pH times).
And a last note: there's really nothing chemically very different about hydroxide dosing like Mike's talking about vs kalkwasser. The difference is that (a) these other forms of hydroxide (especially lye) are WAAAAY more soluble than kalk, so you can dose a pretty hefty amount of additive without adding too much water (common problem of kalk is consumption is higher than the total of the ATO required), and (b) with kalk, if you outpace the rate CO2 is dissolving into the tank, you don't have an alternative except a whole 2-part setup and I've never heard of someone dynamically switching between kalk and 2-part based on pH...but I guess you could? Mike's strategy gives you a good setup because it covers that base very nicely

 

[Brett S]

I have some updates. When I first started looking into this I had ordered some pH calibration solution, since I figured it would make sense to calibrate my probe since I’m going to be playing around with the pH. It arrived before the holidays, but I was busy and never got around to calibrating. I finally calibrated the other day and realized that my pH was actually considerably lower than I thought it was. The probe was reading about .12 low, so while I thought I had been getting into a pretty good range of 8.1-8.2 it was actually more like 7.98-8.08. And before I had been working on trying to get my pH up I’m not sure it ever even got above 8 and during the big dips I was having it might have even been dipping under 7.5.

At this point, since I was all in I decided to go ahead and implement my CO2 scrubber to try to bring up the pH. I still don’t like the idea of using the CO2 scrubber on a daily basis, but I also realized that there may be kind of a chicken and egg effect with pH and alkalinity dosing. With a low pH the alkalinity consumption is low, so I don’t need to dose much alkalinity supplement. But the alkalinity supplement (especially lye) can help boost or maintain the pH, so by not dosing much it doesn’t have much of an effect on the pH. However, if the pH is higher then I will need to dose more alkalinity supplement, and more alkalinity supplement should have a bigger effect on the pH helping to keep it high. So my hope is that by using the CO2 scrubber to raise the pH then that should increase the alkalinity intake, which will increase the amount of alkalinity supplement that I’m dosing, which will then hopefully lessen my dependence on the CO2 scrubber to keep the pH up. That’s my theory, at least.

So here is my pH graph since I calibrated the probe and started using the CO2 scrubber

As I’ve said all along, I don’t want to be making big changes suddenly, so right now I have 8.2 set as my high pH. Once the pH reaches 8.2 the apex will switch from lye to soda ash and turn off the CO2 scrubber. That’s why you can see the plateau at about 8.2 each day. You can also see that the valley is getting higher and higher each day. I have been needing to increase my alkalinity dosing over this time and I think that is the effect. In fact as I’ve been raising the pH through this whole thread I’ve more than doubled the amount of alkalinity supplement that I’ve needed to dose to keep my alkalinity stable.

I also did wind up setting up my CO2 scrubber to recirculate the air through my skimmer and I still have not had to change the media, so at least I’m not burning through a lot of expensive media.

I’ve also been seeing some nice positive effects in my corals. I’ve been seeing some increased growth and coloration on some of them. (Although to be fair, I also started dosing nitrates at about the same time that I started working on pH, so it’s difficult to say how much of an effect each change had on things)

I’m going to continue to fine tune things and bump up that high plateau value a bit and see how things settle out.

I did get my CO2 sensor in the mail yesterday and I got it powered up. For others who decide to buy a similar sensor it’s worth noting that it does not come with a power adapter, but it actually allows a very wide range of power options. You can power it with anything from 18 to 30V AC or 18 to 42V DC. Right now I have it connected with a 24V DC adapter, but I’ll probably just wind up getting one of the apex 24V accessory cables and connecting it to one of my 24V accessory ports so I don’t have an extra power brick in my system.

Interestingly it seems to read about 200PPM higher than my other CO2 meter (but that’s just a reasonably inexpensive plant CO2 meter from amazon). My existing meter says that my typical day to day CO2 level is around 800PPM, which I had thought was pretty good for indoor air, but the new meter says that it is a bit over 1000PPM, which isn’t terrible, but it’s still not great. I’m not sure which I is right and which is wrong, but in the end it probably doesn’t really matter too much as all I really want to see is when the CO2 level increases significantly. I still need to figure out how to get this connected to the apex. I’m not so sure that it has the closed contact output that I thought it did, so the breakout box might not be an option. I may need to just spring for the ASM, but I’ll keep playing with it a bit.

 

[Reefinmike]

I have some updates. When I first started looking into this I had ordered some pH calibration solution, since I figured it would make sense to calibrate my probe since I’m going to be playing around with the pH. It arrived before the holidays, but I was busy and never got around to calibrating. I finally calibrated the other day and realized that my pH was actually considerably lower than I thought it was. The probe was reading about .12 low, so while I thought I had been getting into a pretty good range of 8.1-8.2 it was actually more like 7.98-8.08. And before I had been working on trying to get my pH up I’m not sure it ever even got above 8 and during the big dips I was having it might have even been dipping under 7.5.

At this point, since I was all in I decided to go ahead and implement my CO2 scrubber to try to bring up the pH. I still don’t like the idea of using the CO2 scrubber on a daily basis, but I also realized that there may be kind of a chicken and egg effect with pH and alkalinity dosing. With a low pH the alkalinity consumption is low, so I don’t need to dose much alkalinity supplement. But the alkalinity supplement (especially lye) can help boost or maintain the pH, so by not dosing much it doesn’t have much of an effect on the pH. However, if the pH is higher then I will need to dose more alkalinity supplement, and more alkalinity supplement should have a bigger effect on the pH helping to keep it high. So my hope is that by using the CO2 scrubber to raise the pH then that should increase the alkalinity intake, which will increase the amount of alkalinity supplement that I’m dosing, which will then hopefully lessen my dependence on the CO2 scrubber to keep the pH up. That’s my theory, at least.

So here is my pH graph since I calibrated the probe and started using the CO2 scrubber

As I’ve said all along, I don’t want to be making big changes suddenly, so right now I have 8.2 set as my high pH. Once the pH reaches 8.2 the apex will switch from lye to soda ash and turn off the CO2 scrubber. That’s why you can see the plateau at about 8.2 each day. You can also see that the valley is getting higher and higher each day. I have been needing to increase my alkalinity dosing over this time and I think that is the effect. In fact as I’ve been raising the pH through this whole thread I’ve more than doubled the amount of alkalinity supplement that I’ve needed to dose to keep my alkalinity stable.

I also did wind up setting up my CO2 scrubber to recirculate the air through my skimmer and I still have not had to change the media, so at least I’m not burning through a lot of expensive media.

I’ve also been seeing some nice positive effects in my corals. I’ve been seeing some increased growth and coloration on some of them. (Although to be fair, I also started dosing nitrates at about the same time that I started working on pH, so it’s difficult to say how much of an effect each change had on things)

I’m going to continue to fine tune things and bump up that high plateau value a bit and see how things settle out.

I did get my CO2 sensor in the mail yesterday and I got it powered up. For others who decide to buy a similar sensor it’s worth noting that it does not come with a power adapter, but it actually allows a very wide range of power options. You can power it with anything from 18 to 30V AC or 18 to 42V DC. Right now I have it connected with a 24V DC adapter, but I’ll probably just wind up getting one of the apex 24V accessory cables and connecting it to one of my 24V accessory ports so I don’t have an extra power brick in my system.

Interestingly it seems to read about 200PPM higher than my other CO2 meter (but that’s just a reasonably inexpensive plant CO2 meter from amazon). My existing meter says that my typical day to day CO2 level is around 800PPM, which I had thought was pretty good for indoor air, but the new meter says that it is a bit over 1000PPM, which isn’t terrible, but it’s still not great. I’m not sure which I is right and which is wrong, but in the end it probably doesn’t really matter too much as all I really want to see is when the CO2 level increases significantly. I still need to figure out how to get this connected to the apex. I’m not so sure that it has the closed contact output that I thought it did, so the breakout box might not be an option. I may need to just spring for the ASM, but I’ll keep playing with it a bit.

That graph looks great- only a .1 daily swing! Be sure to keep a bunch of extra 7.0 packets around to periodically check your pH probe. One thing I really like about the alkatronic is that it records the sample pH with every test. the tronic is calibrated with 4.00 and 7.00 solutions while my neptune probe uses 7.00 and 10.00 solutions. comparing values from both systems is an easy way to ensure both probes are calibrated and accurate.

I'm following you on the chicken v egg reference... I've always noted how the more I dose, the higher the pH, the more the reef needs. Since starting all these experiments 3 months ago I've gone from ~200ml a day to near 500ml today. demand increases about 10% every week!

 

[Reefinmike]

Looking at my pH and alk graphs I noticed a trend of alk dipping right around 11pm while pH peaks. Normally pH doesn't break 8.40 but if I'm away for the weekend it will. I added tdata to dose 45ml bicarb or 0.25dkh between 11p and midnight. though my graphs show it's been dosing all week, I didn't plumb the dos to bicarb until ~30 hours ago. I'll let it run like this for a week then my next step is to start lowering my alkalinity to address the unbelievable demand of 4.7dkh/day. The Alkatronic actually reads .5-.7dkh high. I've confirmed it beyond any possible doubt however as with anything, consistency and precision are what matters and I can't complain one bit. My alk is actually 9.1-9.3 and I intend to lower it to 8.5.

even though demand is incredibly high; my reef couldn't be happier. All my corals are doing notably better these past 2 weeks than ever before.

 

[Brett S]

That’s great. I‘m glad things are working for you. Things are going well here, although unfortunately Neptune is out of ASM’s, so I’ll have to wait until late Jan or early Feb to get one. But I‘ve still been allowing the apex to control the use of my CO2 scrubber, letting it turn on if the pH gets too low and also manually turning it on during the times more people are in the house and the CO2 is high. It seems to be working well and my pH has been pretty stable over the past week:

And the amazing thing (to me, at least) is that I had more people in the house starting yesterday evening and by manually enabling the CO2 scrubber the apex has been able to keep the pH very similar to the previous days.

 

[Reefinmike]

looks great! I see you're getting more comfortable with "normal" pH levels. I hooked up my co2 meter last night and it seemed to be reading pretty accurately right out of the box. co2 right around 1200ppm when I'm in the same room :/ . as the tank lights turned off (right next to the home's thermostat) I was in bed and the HVAC started running more. either the hvac is very efficient at introducing new air/dispersing CO2 as there was a very sudden sharp drop. I was gone quite a bit today and it dropped to around 520 by the time I got back home. I'll continue on with my normal nightly routine and see if I get similar trends.

My dashboard is starting to look like NASA's command center... and I love it! disregard the 10.3 alk spike... I moved my ph probe and started dosing to my overflow box to see if dosing to a different area could help with the unbelievably high demand(still no precip)... well that's a bad idea because my tronic draws sample water from the first sump chamber... I'm working on designing some sort of sample/dosing/mixing/feeding box that exchanges display water and expeditiously mixes water with additives. similar to the little mixing chamber with the avast marine plank feeder but much more utility... I call it the "Cloaca" lol!

 

[Reefinmike]

Well, my CO2 meter showed very high levels when I first plugged it in. I'm not entirely sure of how the unit calibrates itself but the way I read it; it constantly recalibrates provided the building goes unoccupied for periods of time... it probably just assigns the lowest reading with atmospheric concentration(410ppm). I guess If I ever see it go below 400 I'll know something's amiss. I'm not too worried about the actual accuracy provided readings remain consistent and shift as expected.

As expected, my pH trends with my lighting which is scheduled to be on when I'm around my reef the most. The CO2 graph also loosely follows that curve because... I'm breathing. What's interesting to see is how anomalies in the pH graph follow the CO2 graph.

 

[Dennis Cartier]

Interesting read about your method of dealing with high levels of CO2 in your home. You may want to look into a HRV/ERV for your home. This would get your CO2 levels (and PH) closer to what you have observed when you were out of the house for extended periods, before any targeted dosing.

I am also using an Alkatronic to modulate my dosing, though in my case, I am using the BNC out to control dosing from a CalRx. No aquarium controller in the mix, just using a Milwaukee PH controller to toggle my Masterflex off when the alk exceeds a limit. Due to the effluent leaving my CalRx being in the 5's, and the 6.2's after my secondary stage, I am adding a final aeration stage to strip the CO2 from the effluent and pin the PH of the effluent to 7.3. I am hoping to see a rise in my PH after it's inclusion.

I already dose kalk in parallel with the CalRx, but varying humidity levels throughout the year make that a limited solution.

Dennis