Computer Controlled CO2

1504 Views 16 Replies 9 Participants Last post by Ben Belton, Sep 25, 2016

PlantGate

Discussion Starter · Sep 23, 2016

I just set up my pressurized CO2 system (Green Leaf) and connected it to one of the outlets on my ReefKeeper Elite system. I haven't set the outlet to anything but "on" yet. But I want to have the system monitor pH and turn on the CO2 if needed. I am a little foggy on how exactly that works. Should I set that outlet to monitor pH and if it rises above 7.5, turn on the outlet for the CO2? I guess I am looking for the threshold number I want to use to control the outlet.

Also I just set up my drop checker so is that a better indicator or is the pH?

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Darkblade48

· #2 · Sep 23, 2016

Generally, you want to set the CO2 to be on to provide a single point drop in pH (a drop of 1 point from what your current pH is at, without CO2 injection).

If your normal pH, without CO2 injection is (say) 7.5, then you would aim for a pH of 6.5.

As such, you would set an upper pH limit of 7.5, and a lower limit of 6.5.

When the pH rises to 7.5, your controller will open the solenoid valve, which will in turn allow CO2 into your aquarium. This will drop your pH until the set lower value (6.5), at which point, the controller will cut power to the solenoid valve, which will stop CO2 injection.

If you have a CO2 controller, I would just use that rather than a drop checker, as the latter really only provides a quick visual check of CO2 levels.

PlantedRich

· #3 · Sep 23, 2016

Not up on the reef system but some info on drop checker versus PH?

When boiled down they both operate on PH. The drop checker is what I would call a modified liquid PH test for color. It relates back to how we use drops in liquid to change the color of the test. So when we use the drop checker, we are waiting for the color change caused by the PH shift. Instead of counting drops to say what PH, we say we have X amount of change when the color changes?
The main difference I see in using the color of a drop checker versus something like a PH meter is the speed and more definite answer of the Meter/probe/monitor. A digital answer versus trying to judge a color is a massive improvement to me. Which is more accurate? Not sure but I get a better vibe with definite answers! Hate judging colors.
Using the Milwaukee PH monitor, I did just set it to turn the CO2 solenoid on when the PH probe measured a certain level. It would then let the CO2 drive the PH down .2 point. This was great for slowly working my PH down and adding more and more CO2 as the fish adjusted over time. As I moved down from 7.8, I got to somewhere around 6.8 and the fish showed distress so I move back up just a touch. I would have found it very hard to do with confidence without a digital number to hit. Kinda green, mid green or really, really green is not much help for me so I no longer use a drop checker.

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LostSouth

· #4 · Sep 23, 2016

Darkblade48 said:
Generally, you want to set the CO2 to be on to provide a single point drop in pH (a drop of 1 point from what your current pH is at, without CO2 injection).

If your normal pH, without CO2 injection is (say) 7.5, then you would aim for a pH of 6.5.

As such, you would set an upper pH limit of 7.5, and a lower limit of 6.5.

When the pH rises to 7.5, your controller will open the solenoid valve, which will in turn allow CO2 into your aquarium. This will drop your pH until the set lower value (6.5), at which point, the controller will cut power to the solenoid valve, which will stop CO2 injection.

If you have a CO2 controller, I would just use that rather than a drop checker, as the latter really only provides a quick visual check of CO2 levels.

Are folks really using that wide of a variance. At a dKH of 4.0, a pH of 6.5 yields 37.9 ppm CO2 and a pH of 7.5 yields 3.8ppm

Hoppy

· #5 · Sep 23, 2016

LostSouth said:
Are folks really using that wide of a variance. At a dKH of 4.0, a pH of 6.5 yields 37.9 ppm CO2 and a pH of 7.5 yields 3.8ppm

It is a mistake to imagine that you can determine how much CO2 you have so that a 3.8 ppm number means something different from a 5 ppm number, or that a 37.9 ppm number means something different from a 40 or 35 ppm number. At the very best we can hope to get enough accuracy to say that we have 5-10 ppm, or 30-40 ppm. If you get your number by using the pH or KH of the tank water your number is just a random number. If you base that number on distilled water containing nothing but sodium bicarbonate, and a well calibrated pH probe you have a reasonable chance of getting it right within 5 ppm or so. If you need to judge a color to get your number, that is more accurate than a random number, but not a whole lot more accurate.

The problem is that relying on pH makes it very difficult, because the calculated ppm is proportional to 10 to the minus pH power, so a tiny mistake in pH makes a big difference in the result.

PlantGate

Discussion Starter · #6 · Sep 23, 2016

Hoppy said:
It is a mistake to imagine that you can determine how much CO2 you have so that a 3.8 ppm number means something different from a 5 ppm number, or that a 37.9 ppm number means something different from a 40 or 35 ppm number. At the very best we can hope to get enough accuracy to say that we have 5-10 ppm, or 30-40 ppm. If you get your number by using the pH or KH of the tank water your number is just a random number. If you base that number on distilled water containing nothing but sodium bicarbonate, and a well calibrated pH probe you have a reasonable chance of getting it right within 5 ppm or so. If you need to judge a color to get your number, that is more accurate than a random number, but not a whole lot more accurate.

The problem is that relying on pH makes it very difficult, because the calculated ppm is proportional to 10 to the minus pH power, so a tiny mistake in pH makes a big difference in the result.

So is the solution to just use your eyes? If the plants are happy and the fish aren't dying, CO2 levels are good? I have been going initially with a 4-5bpm flow rate. I'll see what that does. The probe is brand-new and I have yet to calibrate it that will get done this weekend.

mistergreen

· #7 · Sep 23, 2016

You want relative pH shift, not fixed. Take a reading before CO2 is injected. Say, 7.0, then stop CO2 when it is 6.0.

Also calibrate your pH sensor every so often because all sensors drift. Automated CO2 with faulty sensor can be fatal to your fish.

LostSouth

· #8 · Sep 23, 2016

Wasn't trying to say that the numbers were spot on, but I do believe a 1.0 swing is a relative number with a reasonably accurate pH controller. You are still talking about ~10x change in the level.

PlantedRich

· #9 · Sep 24, 2016

Darkblade48 said:
Generally, you want to set the CO2 to be on to provide a single point drop in pH (a drop of 1 point from what your current pH is at, without CO2 injection).

If your normal pH, without CO2 injection is (say) 7.5, then you would aim for a pH of 6.5.

As such, you would set an upper pH limit of 7.5, and a lower limit of 6.5.

When the pH rises to 7.5, your controller will open the solenoid valve, which will in turn allow CO2 into your aquarium. This will drop your pH until the set lower value (6.5), at which point, the controller will cut power to the solenoid valve, which will stop CO2 injection.

If you have a CO2 controller, I would just use that rather than a drop checker, as the latter really only provides a quick visual check of CO2 levels.

I sometimes go back and reread posts and this sometimes leads me to a different thought than the first read has given me. While discussing PH, I might ask if what I read is what Darkblade meant to say.
I question how he has stated setting the controller as I did find mine quite different. Maybe we are talking about different controllers or I'm not picking up what he is saying. I would have thought letting the PH, driven by the CO2 under control of the controller, swing that far from on to off, would stress my fish.
In my case, normal PH was 7.8 and I started near that level and over time worked it down to try for 6.8 but the controller turned on/off to maintain the PH within .2 of the set point rather than letting it swing a full point before changing.
Are we speaking of different controllers or different methods? I found my fish struggled seriously when moving from CO2 enriched to no CO2 and then back again. This was one reason for me to stop using pressure CO2 on my tank of African cichlids. The females holding eggs were moved form the main tank with CO2 to isolation without CO2 to spit the fry and when moving back to the main tank, they were severely stressed for a couple hours.
Just a question of how we are saying it or a major difference in methods?

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PlantGate

Discussion Starter · #10 · Sep 24, 2016

PlantedRich said:
I sometimes go back and reread posts and this sometimes leads me to a different thought than the first read has given me. While discussing PH, I might ask if what I read is what Darkblade meant to say.
I question how he has stated setting the controller as I did find mine quite different. Maybe we are talking about different controllers or I'm not picking up what he is saying. I would have thought letting the PH, driven by the CO2 under control of the controller, swing that far from on to off, would stress my fish.
In my case, normal PH was 7.8 and I started near that level and over time worked it down to try for 6.8 but the controller turned on/off to maintain the PH within .2 of the set point rather than letting it swing a full point before changing.
Are we speaking of different controllers or different methods? I found my fish struggled seriously when moving from CO2 enriched to no CO2 and then back again. This was one reason for me to stop using pressure CO2 on my tank of African cichlids. The females holding eggs were moved form the main tank with CO2 to isolation without CO2 to spit the fry and when moving back to the main tank, they were severely stressed for a couple hours.
Just a question of how we are saying it or a major difference in methods?

My controller will monitor pH, and do something based on the set point and the hysteresis. I would probably put the set point at maybe 7.0? Then set the hysteresis at .2, specify to turn on the CO2 if it goes above the setpoint plus the hysteresis, or 7.2. I could also set an alarm on the pH level where if it got to a certain level too high or too low I could have it do something (notify me, sound an audible alarm, turn off something, etc.). The sky is the limit with this controller.

klibs

· #11 · Sep 24, 2016

PlantGate said:
So is the solution to just use your eyes? If the plants are happy and the fish aren't dying, CO2 levels are good? I have been going initially with a 4-5bpm flow rate. I'll see what that does. The probe is brand-new and I have yet to calibrate it that will get done this weekend.

Yes monitoring your fish/plants is the best way to determine whether things are working. If you 'calculate' 10ppm of CO2 and things are great, then change things to 'calculate' 30ppm of CO2 and things go downhill then wouldn't you rather stick with your initial rate?

PlantedRich

· #12 · Sep 24, 2016

klibs said:
Yes monitoring your fish/plants is the best way to determine whether things are working. If you 'calculate' 10ppm of CO2 and things are great, then change things to 'calculate' 30ppm of CO2 and things go downhill then wouldn't you rather stick with your initial rate?

I do use what I see as the final answer as to how much is too much but the controller is very handy to make the small gradual move to higher levels. To me there is nothing about our measurement of CO2 to make me think that our calculations of PH or any of the things we measure would be better than watching the fish. I think of it more like the speedometer on a car. Not an item to trust totally to determine how fast to drive but still very helpful.
I would not start at the point I calculated as right because I feel it is far safer and less stress to the fish to move down slowly and watch how they act. I take several days or a week to get from my normal PH down to my final point.
Different fish will react in different ways to changes in their tank water so I never make any sudden moves that can be avoided and do the change when I can be there to watch for at least a few hours.
Where I find the controller very nice is when I reach a point where the fish begin to show stress, it is simple to move the control back a small amount like .2 and watch how they feel. A bubble counter changes very slowly and I could easily gas my fish before it changed colors so I watch them but use the controller for settings.

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Ben Belton

· #13 · Sep 24, 2016

LostSouth said:
Are folks really using that wide of a variance. At a dKH of 4.0, a pH of 6.5 yields 37.9 ppm CO2 and a pH of 7.5 yields 3.8ppm

I would go with what this guy and DarkBlade said. The KH/pH relationship is a guideline. It is not exact, but I'm sure LostSouth was not proposing that it was. It just gives you a place to start. Then you work from there.

So test your KH, use the KH/pH table to set up your equipment, keep an eye on your fish for distress, and see how it goes.
Here is more information
CO2/pH/KH table - Aquarium Plants - Barr Report

Good luck Plant Gate!

robaldorobert2

· #14 · Sep 24, 2016

I use ro water and control the kh by adding back in a kh Booster. (my water is garbage here so ro is my only choice). I use a reefkeeper with a hysteresis of .05 and keep mine at ph 6.7 so it will shift between 6.65-6.75. Plants do great and fish are great. I will warn you still check pH weekly to ensure the probe is calibrated. I killed some fish that way.

Sent from my SM-N910T using Tapatalk

PlantGate

Discussion Starter · #15 · Sep 25, 2016

4

Ben Belton said:
I would go with what this guy and DarkBlade said. The KH/pH relationship is a guideline. It is not exact, but I'm sure LostSouth was not proposing that it was. It just gives you a place to start. Then you work from there.

So test your KH, use the KH/pH table to set up your equipment, keep an eye on your fish for distress, and see how it goes.
Here is more information
CO2/pH/KH table - Aquarium Plants - Barr Report

Good luck Plant Gate!

Thanks! I forgot to mention, I do not have any fish yet and we may decide not to ever get any fish. We'll let it go for a month and see where it goes. BTW: I have 2 temp probes and 2 pH probes on my ReefKeeper (one for the reef tank) and I was monitoring the wrong one for the heater outlet. I was wondering why it was 73 and the heater was off. I specified the temp probe in the marine tank to monitor for that heater. I think I've been working too hard at this! LOL!

Here's a couple of shots - almost done with setup!

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PlantedRich

· #16 · Sep 25, 2016

Working too hard on the setup? Very easy thing to do when starting.
I find there are so many things that change as i move forward on tanks that I now very rarely even plan them but just move onward and keep my main plans centered on adapting things as I find what is working. If went with the same fish,plants and tank setup each time, I might plan something but then I do not want to travel the same route time after time so each tank is a new experience.

From here, it looks like a very nice start with things and it is certain to change as things move on so just set back and watch? No way! Have a plan to adapt things as needed. That is the way nature does it all the time.
But take time to enjoy the trip!

Ben Belton

· #17 · Sep 25, 2016

Your tank looks great. Good luck.

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