If its not CO2, then why low pH

capted

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photos make it so much easier I’ve temporarily linked a hose up from skimmer to outside now will make it properly over weekend. How long till you see any results hours/days/weeks or months
Took about 2 or 3 days to see a steady ph reading.
 
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Rob.bucek

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I ran a pvc pipe right through the house! It's behind the tank so you don't see it in the house. I got lucky with that. If I ever move the tank then it will be a problem. Put an adapter on the end of the pipe for a 3/8" silicone hose that goes to my co2 scrubber then to my skimmer air inlet with a valve if I need to control air flow. Pics not so good but shows what I mean. Going on almost 2 months for the co2 media and it's just starting to exhaust. Also the scrubber has 1/2' ports for more airflow. Oh and I glued some window screen to the outside elbow to keep bugs out of the line.
This is awesome, thank you so much!
 

capted

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I can see mine change same day (4-6 hours), perhaps it has to do with the amount of air the skimmer brings in.
Yes, I saw an increase but not much at first. 24hrs it was more noticeable rising. What size tank do you have? Mine is 125gal and I have alot of surface agitation plus fans in my hood for the LEDs so I get a lot of house air with co2 in the water which may explain the longer time it took to kind of stabilize. I'm just thrilled how long my co2 media is lasting! Too expensive to replace weekly or every 2 weeks. If that was the case I would just run outside air only.
 
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Randy Holmes-Farley

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Whether various treatments to raise pH are successful depend on many factors, not least of which is how much aeration with the indoor high CO2 air is taking place. Many reef aquaria have quite a bit of aeration at the tank top.
 

josephxsxn

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Whether various treatments to raise pH are successful depend on many factors, not least of which is how much aeration with the indoor high CO2 air is taking place. Many reef aquaria have quite a bit of aeration at the tank top.

Great point, I have very minimal top water agitation going on with the display, almost all gas exchange is supported by the skimmer with outdoor airline.
 

kilnakorr

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It’s just shocking to think that even a small skimmer, with a recirculating CO2 scrubber, with air pulled from outside, doesn’t have the ability to overcome the surface area of a 396 square inches, and at most makes minimum impact.

That’s why I was baffled and thought this is occurring from a biological process of decay. Not dead animals, but bacteria and alike.

Makes me wonder the air volume required to be injected from a skimmer VS the surface area of the tank to make a meaningful impact. I saw an positive impact from the aeration of water test, but I wonder if one could make a formula to guide a sizing recommendation to picking a proper size skimmer
I had the exact same problem.
Kalkwasser, CO2 scrubber and nothing had a major effect.
Since the media in my scrubber lasted a looooong time, It finally hit me:
The skimmer air was turned way down, as my sump was not built for this skimmer and with no room to raise it, it was sitting very deep, anf air intake restricted.
Just a few days ago I moved it to the return chamber, and opened up the air intake.
Today I got a 8.10 - 8.22 reading (morning to now. Two days ago it was 7.89 in the morning.

It is probably the skimmer / air volume that isn't big enough to have an impact.
 

Rob.bucek

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I had the exact same problem.
Kalkwasser, CO2 scrubber and nothing had a major effect.
Since the media in my scrubber lasted a looooong time, It finally hit me:
The skimmer air was turned way down, as my sump was not built for this skimmer and with no room to raise it, it was sitting very deep, anf air intake restricted.
Just a few days ago I moved it to the return chamber, and opened up the air intake.
Today I got a 8.10 - 8.22 reading (morning to now. Two days ago it was 7.89 in the morning.

It is probably the skimmer / air volume that isn't big enough to have an impact.
I was considering throwing a second skimmer into my sump just to see the impact. No collection of skimmate, just let it go straight back into the sump and draw outside air to it in order to remove the indoor CO2 factor in order to see what that added aeration does for the pH if anything.
 
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Biologic

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I had the exact same problem.
Kalkwasser, CO2 scrubber and nothing had a major effect.
Since the media in my scrubber lasted a looooong time, It finally hit me:
The skimmer air was turned way down, as my sump was not built for this skimmer and with no room to raise it, it was sitting very deep, anf air intake restricted.
Just a few days ago I moved it to the return chamber, and opened up the air intake.
Today I got a 8.10 - 8.22 reading (morning to now. Two days ago it was 7.89 in the morning.

It is probably the skimmer / air volume that isn't big enough to have an impact.

I was considering throwing a second skimmer into my sump just to see the impact. No collection of skimmate, just let it go straight back into the sump and draw outside air to it in order to remove the indoor CO2 factor in order to see what that added aeration does for the pH if anything.

I like both of these perspectives, and I am already implementing this. I've recently purchased a DELTEC MCE-601 hang on back protein skimmer. The air is being pulled from outside, the same as the previous smaller Deltec MCE-300. https://deltecdirectusa.com/collect...ts/deltec-mce600-hang-on-hob-protein-skimmers

For it's size, its rated 130 Gallons at heavy stocking, let's take that tank rating at a grain of salt, I put this on a 28 gallon JBJ nano cube to boost pH. So far, I've seen a positive affect on pH in 24 hours. The jury is still out on over all affect, but its impact thus far has been positive on the dinural low. I will share results Friday.

I would be curious to add another skimmer to see if that would further reduce the over all swing, but at this point, adding another HOB skimmer to this small of a tank, will throw the water volumes off too much, and mess up dosing.
 

sunken3

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(apologize in advance.. i haven't read all the posts).. i had the same issue.. CO2 scrubber didnt really help, i have 2 sumps attached to my main tank and one of them is actually outside... (as well as my ATO and AWC).. seems my "daily" AWC was the culprit.. i moved to once every 2 weeks and the issue went away... makes little sense to me, but hey.
 
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(apologize in advance.. i haven't read all the posts).. i had the same issue.. CO2 scrubber didnt really help, i have 2 sumps attached to my main tank and one of them is actually outside... (as well as my ATO and AWC).. seems my "daily" AWC was the culprit.. i moved to once every 2 weeks and the issue went away... makes little sense to me, but hey.

Wow, I appreciate the input. I certainly have to keep that in mind. I've turn my AWC off for the moment while testing this, but my auto top off is still in service. I am going to stick a pH probe in there and take a look. I use to use kalkwasser in the auto-top off bin, but I removed that to test the issues here.
 

blasterman

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C02 scrubbers don't work for me either. Ive even used liquid lye as a media and blasted the tank with a venturi and it didn't do much to day pH. Night pH went up, but I've not found night pH to matter much for SPS growth. So I've shelved CO2 scrubbers.

My theory on scrubbers being hit and miss is that they are trying to keep tank CO2 levels less than room CO2 levels, and its a battle they can't win. Your tank surface is constantly loading back up with CO2. Anybody who's CO2 dosed a FW tanks knows how fast CO2 absorbs in water.

Kalk drives my SPS alk usage up dramatically, but I would need half a gallon of kalk per day to keep up and its mathematically impossible on my small tank.

I tried sodium hydroxide last week and that worked dramatically, but I had the doseage too high and had to back down and am trying a more controlled test tomorrow. My tank will not exceed 8.10-8.15 next to an open slider, and I need at lease a point higher. My acropora struggle unless pH is higher and 8.3 to 8 4 doubles my alk uptake. If I get good results with sodium hydroxide I will post a thread.
 

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Good point about the awc. When I do my manual water changes the ph drops from 8.3 to 8.0 for some time. Most likely because my holding tank for the new water is in the same house with a slightly high co2 level. The tank ph will bounce back up after 30 minutes or so.
 
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C02 scrubbers don't work for me either. Ive even used liquid lye as a media and blasted the tank with a venturi and it didn't do much to day pH. Night pH went up, but I've not found night pH to matter much for SPS growth. So I've shelved CO2 scrubbers.

My theory on scrubbers being hit and miss is that they are trying to keep tank CO2 levels less than room CO2 levels, and its a battle they can't win. Your tank surface is constantly loading back up with CO2. Anybody who's CO2 dosed a FW tanks knows how fast CO2 absorbs in water.

Kalk drives my SPS alk usage up dramatically, but I would need half a gallon of kalk per day to keep up and its mathematically impossible on my small tank.

I tried sodium hydroxide last week and that worked dramatically, but I had the doseage too high and had to back down and am trying a more controlled test tomorrow. My tank will not exceed 8.10-8.15 next to an open slider, and I need at lease a point higher. My acropora struggle unless pH is higher and 8.3 to 8 4 doubles my alk uptake. If I get good results with sodium hydroxide I will post a thread.

I feel you with the small tank. I am trying not to let size limit what I can do on this small tank, as I want to get back into a larger tank one day. So this is proof of concept that has to be scaled.

I am hesitant to try NaOH because of potential of alkalinity contribution (swings) + throwing salinity off. Likewise, CaOH throwing off Calcium.

Is the consumption from your corals, greater than what's being contributed from the NaOH? Are there any alkalinity swings at night as a result of dosing at night? Care to share how you are doing this?
 

Rob.bucek

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C02 scrubbers don't work for me either. Ive even used liquid lye as a media and blasted the tank with a venturi and it didn't do much to day pH. Night pH went up, but I've not found night pH to matter much for SPS growth. So I've shelved CO2 scrubbers.

My theory on scrubbers being hit and miss is that they are trying to keep tank CO2 levels less than room CO2 levels, and its a battle they can't win. Your tank surface is constantly loading back up with CO2. Anybody who's CO2 dosed a FW tanks knows how fast CO2 absorbs in water.

Kalk drives my SPS alk usage up dramatically, but I would need half a gallon of kalk per day to keep up and its mathematically impossible on my small tank.

I tried sodium hydroxide last week and that worked dramatically, but I had the doseage too high and had to back down and am trying a more controlled test tomorrow. My tank will not exceed 8.10-8.15 next to an open slider, and I need at lease a point higher. My acropora struggle unless pH is higher and 8.3 to 8 4 doubles my alk uptake. If I get good results with sodium hydroxide I will post a thread.
There's some people out there running with Kalk slurry to overcome that EVAP limitation. I'm currently experimenting with it myself using a 4% kalk solution (looks like milk). It's 24 times stronger so you need far less volume wise. One guy is dosing the equivalent of 30 gallons a night on his system to meet demand.
 
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Biologic

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I promised this update now that I have a larger Deltec MCE 601 HOB skimmer. It claims it pulls in 400 liters/hour of air. Looking at the air pulling in, its definitely more than my previous skimmer which only pulled 150 liters/hour. The air is pulled from outside.

Here's an average week --

1624715386709.png


Average Low -- 7.83 // Absolute Low -- 7.8
Average High -- 8.14 // Absolute High -- 8.18
Average -- 7.99
Average Diurnal Swing -- 0.31

Now here's when I added my new skimmer. Starts at the very beginning of the data, in the after noon of June 22.

1624715796551.png


Average Low -- 7.95 // Absolute Low -- 7.87 (which I was cleaning out my all-in-one sump, and disturbed the detritus which absolutely pulls down pH)
Average High -- 8.21 // Absolute High -- 8.22
Average -- 8.07
Average Diurnal Swing -- 0.26

Discussion --

So the biggest difference I notice is not necessary the higher pH during the day time its the average 0.12 difference in low pH! So the bigger skimmer is affecting diurnal swing at night. Which keeps the difference from day to night. I do appreciate the tiny 0.07 average High bump. The diurnal swing is a tad smaller 0.31 vs 0.26, which my goal is to decrease that as well. This is a satisfactory results in my opinion. Not amazing CO2 scrubber results, but cheaper in the long run with less maintenance.

Thing's that I see that affect pH is when it rains. Yes, when it rains, I find the pH is slightly lower, I guess from carbon sequestration from the upper atmosphere brought down lower atmosphere? I still need to get a meter to see if that can be observed. I've noticed that especially with this larger skimmer.

Conclusion --

Overall, having a larger oversized skimmer with air pulled from outside will help before moving onto more invasive forms of pH management such as kalkwasser.
 

Rob.bucek

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I promised this update now that I have a larger Deltec MCE 601 HOB skimmer. It claims it pulls in 400 liters/hour of air. Looking at the air pulling in, its definitely more than my previous skimmer which only pulled 150 liters/hour. The air is pulled from outside.

Here's an average week --

1624715386709.png


Average Low -- 7.83 // Absolute Low -- 7.8
Average High -- 8.14 // Absolute High -- 8.18
Average -- 7.99
Average Diurnal Swing -- 0.31

Now here's when I added my new skimmer. Starts at the very beginning of the data, in the after noon of June 22.

1624715796551.png


Average Low -- 7.95 // Absolute Low -- 7.87 (which I was cleaning out my all-in-one sump, and disturbed the detritus which absolutely pulls down pH)
Average High -- 8.21 // Absolute High -- 8.22
Average -- 8.07
Average Diurnal Swing -- 0.26

Discussion --

So the biggest difference I notice is not necessary the higher pH during the day time its the average 0.12 difference in low pH! So the bigger skimmer is affecting diurnal swing at night. Which keeps the difference from day to night. I do appreciate the tiny 0.07 average High bump. The diurnal swing is a tad smaller 0.31 vs 0.26, which my goal is to decrease that as well. This is a satisfactory results in my opinion. Not amazing CO2 scrubber results, but cheaper in the long run with less maintenance.

Thing's that I see that affect pH is when it rains. Yes, when it rains, I find the pH is slightly lower, I guess from carbon sequestration from the upper atmosphere brought down lower atmosphere? I still need to get a meter to see if that can be observed. I've noticed that especially with this larger skimmer.

Conclusion --

Overall, having a larger oversized skimmer with air pulled from outside will help before moving onto more invasive forms of pH management such as kalkwasser.
@Biologic thank you so much for this data. Very well done sir. I am in the process of looking for another skimmer to test this very theory. I'm convinced the surface agitation in my tank overwhelms any benefit my current skimmer brings, even with drawing outside(ish) air. I'll be doing a project this week to improve my air draw. I will return the effort and post my before and after results here as well. My plan, install an external recirculating skimmer in addition to the internal one in place. I will collect skimmate from the external and just run the internal as an overflow with no collection. Be interesting to see the results.

Interesting to note that I purchased a CO2 meter and the room runs around 800 normally and peaks over a 1,000 of I'm in it for a couple hours. If I leave the windows all open it drives down to 450 and I see over a full point increase in my pH.

Nice work.
 
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@Biologic thank you so much for this data. Very well done sir. I am in the process of looking for another skimmer to test this very theory. I'm convinced the surface agitation in my tank overwhelms any benefit my current skimmer brings, even with drawing outside(ish) air. I'll be doing a project this week to improve my air draw. I will return the effort and post my before and after results here as well. My plan, install an external recirculating skimmer in addition to the internal one in place. I will collect skimmate from the external and just run the internal as an overflow with no collection. Be interesting to see the results.

Interesting to note that I purchased a CO2 meter and the room runs around 800 normally and peaks over a 1,000 of I'm in it for a couple hours. If I leave the windows all open it drives down to 450 and I see over a full point increase in my pH.

Nice work.

I am planning on an external recirculating skimmer myself for a larger build. I know I suggested this in the thread, but it would be great if there was a way to make a standard prediction for recommending air draw vs volume = effect on pH.

If I would use this estimate 400 liter per hour air / 28 gallons = 14.3 liters per gallon rating in my set up in my environment

So if I wanted a 175 gallon tank, I need an air draw of around 2,500 liters per hour to get similar performance in pH. Though i do understand there’s many other variables in play, like life stock differences and equipment variables.
That’s a very large skimmer, but I’m crazy enough to do it. I can always throttle back the skimmer flow rate, and air draw.
 
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