New Yugang Testing

[hamfist]

Yeah, I'm definitely not using a diffuser. After some additional observation, I do think this is a case of air bubbles getting smashed into micro bubbles and passing right though the reactor. Surprising that it can appear as small as diffused CO2 mist but it's the most reasonable explanation. Made some adjustments to the skimmer and wasn't as noticeable today.

It certainly seems to fit the evidence. I'm glad you seem to have improved things.

 

[marekm]

I realize that it might be helpful to explain how to actually dial in a CO2 setup!

First, you have to keep as many variables constant as possible. If you are constantly changing these, it makes it VERY hard to dial in CO2 injection:

Things that change CO2 levels in the water are:

• Injection rate (bubbles per second for bubble counters, or SCCM if using flowmeter. Also rotatable/adjustable horizontal reactors)
• Temperature (warmer = less CO2, colder = more CO2)
• Surface agitation (how near your filter/lily pipe is towards the surface of the water)
• Surface scum (more scum=more CO2. Skimmers help remove scum)
• Time CO2 injection started (injecting earlier allows more time to reach CO2 equilibrium)

Here's a real example of how I get an aquarium CO2 dialed in with only drop checkers and the Hanna CO2 test kit​

This is WAY easier to do without fish/shrimp/snails, since there's no danger if you "over-inject" CO2.

1) I get everything set up. Tank, hardscape, light, filter, etc. I set my inline heater to a constant 74F. I lock my lily pipes in place, and check that I like the flow and surface agitation, and my skimmer is set up properly. I get a drop checker filled and installed. Once these things are how I like, I keep them there and don't **** with them. This is also easier to get setup without plants, so you don't have to worry about unhappy plants while dialing in the setup.

2) I start CO2 injection in the evening at a level I think might be appropriate. I let it inject CO2 all night. I don't worry or care about wasting CO2. I try to inject for at least 8-10 hours or more.

3) In the morning of Day 1, I check the drop checker and take a CO2 reading with the Hanna test kit. By injecting CO2 for ~10 hours, I can be sure I've reached whatever equilibrium level this current CO2/min injection setup is going to hit. If I like what I see (around 30-35ppm CO2, usually), I don't change a anything. I now set up my CO2 solenoid timer to come on anywhere from 3-5 hours before the lights normally would, and turn the CO2 off for the remainder of this day. This step is used to determine what the actual ppm the injection/offgassing equilibrium reaches with my setup.
If I'm injecting too much CO2, I reduce the CO2/min rate on my needle valve or rotate my horizontal reactor (if running in overflow mode), and try again in 8-10 hours. Same for if I'm injecting too little.

4) Once I get the equilibrium-over-time level to the ppm CO2 I want, it's time to dial in the timer setup. I let the CO2 timer turn the solenoid on for the first time automatically in the early morning. At 9am (aka whenever I want lights to come on) I take a Hanna CO2 reading and check the DC. If the reading is within 5-7ppm of my targeted 30-35ppm CO2, I'm probably injecting early enough. If it's only at 20 or 25ppm CO2, and I haven't changed anything, then I know I will need to start CO2 injection earlier in the day. This stem is used to determine AT WHAT TIME IN THE MORNING I need to start the previously-determined CO2 injection rate to reach near my desired 30-35ppm CO2 injection for the entire duration of the photoperiod.

5) If I like what I see, I let the CO2 inject normally as I would for the photoperiod. At 4pm, I take a Hanna CO2 reading and check my DC too.
If the reading at 4pm (or whenever you want CO2 to turn off) is at ~35ppm CO2, I've nailed it! If it's at 40 or 45+ ppm CO2, I'm injecting too much CO2/min.

6) For the next few days, I take a CO2 test reading at 9am (lights on) and at 4pm (CO2 off). If my CO2 level is ~30ppm at lights on, and ~35ppm at CO2 off, this setup is perfect.

And I'm done! I never have to worry about it again, right? Unless... If I adjust anything in a major way, I will need to do the same to dial it in. For example:

• Installing a more powerful filter will increase the flow, which changes the surface agitation and therefore the offgassing rate. Might need to dial in my CO2 again.
• Bumped my lily pipe and I can't remember how high I had it set up before. Might need to dial in my CO2 again.
• Went from 68F unheated room temp to an 86F discus tank. Might need to dial in my CO2 again.
• My CO2 cylinder ran out of CO2, and I had to install a new one which involved closing my regulator dials. Might need to dial in my CO2 again.

The easiest way to dial in your CO2 with a Hanna test kit is to simply start injection earlier in the morning than normal, and take a reading after 4-6 hours. The longer you give your CO2 time to inject, the more certain of the equilibrium level you can be. I usually find that anywhere from 4-6 hours is the minimum to get within 90% of the equilibrium rate, though in some setups it might take longer.

If your actual equilibrium level is 30-35ppm for 90% of the photoperiod, you will experience the best growth you've ever seen with your plants.

Regarding switching CO2 cylinders, is closing the regulator dial mandatory during the switch? I assume it can damage the regulator if the dial is not turned off? That is quite a bummer tbh, to have to fiddle with the needle valve for 1-2 days after each cylinder switch.

 

[Pepere]

Obviously, I can crank up the injection rate, but I expected my injection rate to actually be reduced from what I'm used to, not more.

Given that the horizontal reactor is at low pressure (the pressure is at,ospheric plus the weight of the water column, well under 1 psi above ambient air pressure) whereas a ceramic diffuser the has significant pressure behind it, the bubbles in the bubble counter are at significantly lower pressure. A bubble under significant pressure is the same size as one that forms at higher pressure, but the amount of co2 molecules will be vastly different. In essence not all bubbles have the same amount of co2 in it so you really cant compare the bubble counter between the two.

I use my pressure knob as my fine adjust,ent screw. I initially turn it to full oressure and fill the reacotr chamber with the needle valve until I get overflow. I then back it off until overflow is down to every 5 seconds or so and then leave it at that level for about 10 minutes. Then slightly close the needle valve to get to where overflow is every 30 seconds or so, allowing a good 20 minutes or so between adjust,ents…. Once I get to that point I switch to the regulator pressure knob, Lowering it by 5 psi at a time. And checking on results after half an hour. I continue dropping pressure until I get to a puge of gas every minute to minute and a half.

Let the tank rin like this for at keast 24 hours.

The next day, check ph right before the co2 comes on. Retest every hour until ph stops dropping. Now you know how many hours it takes for ph to stop dropping after co2 comes on and reaches equilibrium…

Thats how long the co2 should be turned on before lights on. Adjust your solenoid timer accordingly.

 

[Art]

* Quick side note: Thank you to all for making this an awesome thread. I've featured it. Also, HUGE thanks to @Naturescapes_Rocco for a fantastic post on dialing in CO2. I've converted it into an article. *

 

[hamfist]

Given that the horizontal reactor is at low pressure (the pressure is at,ospheric plus the weight of the water column, well under 1 psi above ambient air pressure) whereas a ceramic diffuser the has significant pressure behind it, the bubbles in the bubble counter are at significantly lower pressure. A bubble under significant pressure is the same size as one that forms at higher pressure, but the amount of co2 molecules will be vastly different. In essence not all bubbles have the same amount of co2 in it so you really cant compare the bubble counter between the two.

I had honestly not considered this before but of course its basic science really. Genius !

 

[Naturescapes_Rocco]

Regarding switching CO2 cylinders, is closing the regulator dial mandatory during the switch? I assume it can damage the regulator if the dial is not turned off? That is quite a bummer tbh, to have to fiddle with the needle valve for 1-2 days after each cylinder switch.

You've got it right. This is one of the reasons why I love Flowmeters - they aren't just great for dialing in CO2, they also allow for easy cylinder tank swaps!

Yes, you can (and will) damage your CO2 regulator if you don't close the main valve fully before removing and reinstalling a cylinder. Also, make sure once the cylinder is attached, you open the main valve SLOWLY, both on the cylinder and on the regulator. Then adjust your needle valve from there.

What's so amazing about using a flow meter set up a bubble counter, is that it measures recitative flow of a gas, in a repeatable manner.

For example, I know that on my experiment tank, with my current set up, I need about 15 SCCM on my flowmeter during CO2 injection.

When my cylinder runs out, and I have to put a new one, all of the dials will be a little bit different when I attach the new cylinder. Having to dial in a bubble counter with a crappy needle valve (looking at you, FZONE) all over again is horrible. Especially when it can take a day or two for it to finally settle in.

With a flow meter, I just attach the new cylinder, adjust the dials until I get 15 SCCM again, and I'm good to go.

The only downside to flow meters are that there is a minimum tank size for them, because flowmeters don't really work in the ultra low ranges that nano tanks require. If you have a small to medium size tank, chances are you are stuck with a bubble counter.

If your tank is 30 gallons or more, you could probably use a flow meter. If it's 50 to 60 gallons or more, you can definitely use a flow meter.

 

[Pepere]

Yes, you can (and will) damage your CO2 regulator if you don't close the main valve fully before removing and reinstalling a cylinder. Also, make sure once the cylinder is attached, you open the main valve SLOWLY, both on the cylinder and on the regulator.

Also not a bad practice to crack open the main valve to blow out any dust or debris that could be in the threaded outlet before attaching your regulator to the tank.

 

[marekm]

You've got it right. This is one of the reasons why I love Flowmeters - they aren't just great for dialing in CO2, they also allow for easy cylinder tank swaps!

Yes, you can (and will) damage your CO2 regulator if you don't close the main valve fully before removing and reinstalling a cylinder. Also, make sure once the cylinder is attached, you open the main valve SLOWLY, both on the cylinder and on the regulator. Then adjust your needle valve from there.

What's so amazing about using a flow meter set up a bubble counter, is that it measures recitative flow of a gas, in a repeatable manner.

For example, I know that on my experiment tank, with my current set up, I need about 15 SCCM on my flowmeter during CO2 injection.

When my cylinder runs out, and I have to put a new one, all of the dials will be a little bit different when I attach the new cylinder. Having to dial in a bubble counter with a crappy needle valve (looking at you, FZONE) all over again is horrible. Especially when it can take a day or two for it to finally settle in.

With a flow meter, I just attach the new cylinder, adjust the dials until I get 15 SCCM again, and I'm good to go.

The only downside to flow meters are that there is a minimum tank size for them, because flowmeters don't really work in the ultra low ranges that nano tanks require. If you have a small to medium size tank, chances are you are stuck with a bubble counter.

If your tank is 30 gallons or more, you could probably use a flow meter. If it's 50 to 60 gallons or more, you can definitely use a flow meter.

thanks for clarification.
what kind of flow meter are you refering to? didnt hear about that before...

 

[Naturescapes_Rocco]

I recommend a Dwyer 151-RMA, the 5-50CC/min model. Price point is just right for what you get, IMO.

You don't need the model with a valve if you can just use your regulator's needle valve.

 

[JayP]

I recommend a Dwyer 151-RMA, the 5-50CC/min model. Price point is just right for what you get, IMO.

You don't need the model with a valve if you can just use your regulator's needle valve.

Someone mentioned purchasing and testing a less expensive lower range flow meter off AliExpress but I don't remember what thread that was in. Curious how that worked out, if it's been tested yet.

 

[hamfist]

I recommend a Dwyer 151-RMA, the 5-50CC/min model. Price point is just right for what you get, IMO.

You don't need the model with a valve if you can just use your regulator's needle valve.

Question - WHich connectors do you like to use to connect standard 6/4mm CO2 line ?

 

[Naturescapes_Rocco]

Question - WHich connectors do you like to use to connect standard 6/4mm CO2 line ?

Good question, I should include that in the future when I respond!

I believe I use these:

 

[Scaper26]

Quick note on pH drop as a tool for CO2:
I've tested extensively in different KH tanks, and find that "pH drop" methods vary as wildly as trying to read a "ppm number" from drop checkers colors. A 1.0pH drop (from degassed) does not equal 30ppm in low KH tanks, or high KH tanks. The range seems to be between 3-6KH for a 1.0pH drop to equal 30ppm CO2. You will need 1.2-1.5 at 0-1KH for ~30ppm CO2, and 0.8pH drop at 6-10KH for 30ppm CO2. For me, it's just not accurate and has too many factors!

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The basics​

What pH readings are most useful for:
Since CO2 injection is directly chemically related to pH drop, we can use pH readings over the course of a day to get an idea of how our CO2 is actually functioning.

Best choice for accurate CO2 ppm readings:
I now have a year of extensive testing and use of the Hanna CO2 Titration kit, and I consider it required for really dialing in CO2 levels.

Combining a pH graph with readings from the Hanna CO2 test kit give us this:

View attachment 12040
This is a real 24-hour graph selection from my current 140p tank with a horizontal "yugang" reactor. Let's break it down:

• I start CO2 injection at 4:00am.
• My lights come on at 9am (yellow part of the graph). By this point, the Hanna CO2 kit is usually about 30ppm CO2.
• CO2 injection continues through the photoperiod.
• At 4pm, CO2 injection turns off. This is the longest point since injection started and should have the most CO2, which checks out on the graph. The Hanna kit usually gives me ~40ppm CO2

Here's the most important parts of this information for me:​

• With my current CO2 setup (lily pipe height for surface agitation, CO2 injeciton rate, filter flow rate, water temperature) it takes about 5-6 hours to truly hit the equilibrium point between injection and offgassing. If I kept injection going after 5pm, the graph should look like this:

View attachment 12043
The pH graph shows me I've reached the actual equilibrium point over time, while the Hanna kit lets me know what my CO2 ppm actually IS at that equilibrium point. This point, with my current setup, is ~40ppm CO2. While this is considered on the "high" side, it's totally acceptable because I also have lots of oxygen in the tank thanks to lots of surface agitation from my filter setup. Fish, shrimp and snails are unbothered, but not all species tolerate or like 40ppm CO2.

I could leave CO2 injection going 24/7, and my CO2ppm would barely shift. This is how I know I'm at equilibrium, when the pH level OR measured CO2 level no longer moves up or down.

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Example 1: Where many hobbyists go wrong with CO2 injection rate​

They start injecting CO2 too late, AND with too much CO2/min, where the eventual equilibrium is too much CO2 AND the photoperiod has massive swings in CO2 levels over time:

View attachment 12044

Simply increasing the needle valve on your regulator to inject "more" CO2 is not the answer -- in fact, it can lead to dangerous levels of CO2 in your aquarium. If you test with the Hanna kit, and your CO2 is 20ppm at lights on, and 45ppm at lights off, you're doing CO2 injection poorly. This is where I believe 50% of hobbyists reside. Plagued by algae and poor plant growth, clearly uncomfortable inhabitants, and "convinced that CO2 isn't the issue because the drop checker is yellow by 3pm".

The single best thing you can do to improve plant growth with CO2 in your tank is to inject earlier in the morning, often starting in the early morning (depending on your setup).

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Example 2: Not injecting too much CO2/min, but not starting early enough either:​

View attachment 12045

The equilibrium we reach is more appropriate around 30ppm, but we only reach near it for half of the photoperiod. This isn't ideal for our plants, which want steady levels of good CO2 for the whole photoperiod duration. This is where probably 30% of hobbyists reside.
It works, plants grow, but they could get FAR better growth over time if they just started injection earlier...

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Example 3: How to properly inject CO2​

View attachment 12052
This is the holy grail of CO2 setups. The water is saturated with steady levels of CO2 for the plants to use before the lights even come on.
90% of the photoperiod is occurring with 25-30ppm CO2 in the water. However, despite starting injection super early in the morning, the maximum level reached stays at/around the target level, and never pushes the tank into "fish-gassing" levels of CO2.

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Answering your question directly:

For me, I start ~5 hours before the lights come on. This is because injection rate and equilibrium are tied together with a horizontal reactor.
If my goal is to have 30ppm within 1hour of injection, I can do that easily by cranking the BPS/rate of CO2! However, it will look like this:
View attachment 12053

It seems that with reactors, because rate+equilibrium are connected, you have to account for such a thing.


Horizontal reactors might simply need more time to dissolve CO2 in the water, technically, than with diffusers. However, they are EXTREMELY efficient at doing so -- it just might take much more time to reach an equilibrium, since rate and equilibrium are tied together with a horizontal reactor. You will still, with a proper setup, use less CO2 with a reactor over time.


I think you'll find that if you start CO2 much earlier, you will be able to reduce the injection rate quite a lot and still maintain the equilibrium you want.

Let me know if you (or anyone) has questions or comments!

This is such a great write up. I was curious about what factors you have noticed that affect CO2 ppm at lower and higher kH. I have always used Dennis’s theory of 30 ppm at 1pH drop and have verified this info on my tanks where the KH is 0-1 and the pH drop is 1.3, so theoretically my CO2 should be around 55 ppm give or take. I know there’s always some variance depending on how much CO2 is dissolved at basline pH, which is why I also use a drop checker along with my 1.3 pH drop to verify that they align somewhat ( I verify that the checker turns visibly yellow at 1.3 pH drop). So along with the info from Dennis’s experiments and theory, the checker turning yellow at 1.3 pH drop (measured with a good pH pen), has me believing that my CO2 is infact above 45 ppm at least. Could I be wrong? Am I injecting less than I think? Because I have heard people who inject 1.5 pH drop and the hanna kit tells them that the CO2 concentration is only 50 ppm, which I would assume to be more so around 65ppm give or take. This is what makes me doubt if there are factors . Like why does my drop checker turn bright yellow at 1.3 pH drop while my KH is 0, indicating 50+ppm. While someone else’s hanna kit says their CO2 level is just 50 ppm even at a 1.5 pH drop.