C02 Diffuser size? Other questions?

[EVoyager31]

Going to be setting up c02 in my 75g heavily planted tank. I've done much research but most of everything online is very generalized when it comes to diffuser size and how many drips/minute I will need. 

Diffuser size: What size should I look for? I'm looking at glass/ceramic diffusers online, and I know I will likely need something a little larger but WHAT SIZE? mm, inches, WHAT. I understand that the bubbles should be very fine so they can diffuse properly before reaching the surface, but does the size of the diffuser affect this?

Drops/minute: How do I measure how much c02 I need? I understand that I can get a c02 drop checker and that the liquid will change colors but do I just play with the c02 output until the liquid turns green or is there something else I should be doing to measure this? If its only going to be on while the light is on, I want to make sure I have enough c02 for them to use.

Also, where would be proper placement of the diffuser inside the tank? Everything I read just says it needs to be somewhere with high flow so it can distribute around the tank but towards the bottom so the bubbles can diffuse. I have a spray bar that is fairly long, so I figure I could just have it low in the tank under that. Only thing is that I have it angled so the flow of the water doesn't disturb my newish (not many roots yet) stem plants. Would this placement work anyway?

I really want to make the right choices with this...plants are expensive and I NEED some success 🙂 

 

[Sumson]

Diffuser Size:

For a tank that large, its better to do an external co2 reactor or inline diffuser to get adequate co2 levels in your tank. If you do decide to do a diffuser then you're right it'll be better to get a larger one. The size of the diffuser should not impact the size of the bubbles that come out because that relies on the material that the diffuser disk is made of.

Drops/minute:

So this is bubbles per minute and this is an old inaccurate way of measuring co2 because each bubble counter will have different amounts of co2. So if I'm doing 30 bubbles per minute it could be drastically different than someone else also doing 30 bubbles per minute. This explains a good way to measure for good co2 levels. You check your Kh and Ph values and compare it to the chart. Anything in the green is good levels of co2 while blue is deficient and red is too much. I added a photo of the chart down below. Drop checkers can work but they take around 1-2 hours to change colours. It is also important that co2 turns on 30 minutes to an hour before the lights turn on the make sure there are adequate levels of co2 for the plants when the lights turn on.

Diffuser flow:

If you do decide to a diffuser, you want to have a circular flow across your tank to make sure you have even co2 levels across your tank. The photo I put below will show a good example of how the flow of your tank can be to ensure good circulation of co2. It came from here.

 

Edited December 19, 2021 by Sumson
more info

[EVoyager31]

On 12/19/2021 at 12:15 PM, Sumson said:

Diffuser Size:

For a tank that large, its better to do an external co2 reactor or inline diffuser to get adequate co2 levels in your tank. If you do decide to do a diffuser then you're right it'll be better to get a larger one. The size of the diffuser should not impact the size of the bubbles that come out because that relies on the material that the diffuser disk is made of.

Drops/minute:

So this is bubbles per minute and this is an old inaccurate way of measuring co2 because each bubble counter will have different amounts of co2. So if I'm doing 30 bubbles per minute it could be drastically different than someone else also doing 30 bubbles per minute. This explains a good way to measure for good co2 levels. You check your Kh and Ph values and compare it to the chart. Anything in the green is good levels of co2 while blue is deficient and red is too much. I added a photo of the chart down below. Drop checkers can work but they take around 1-2 hours to change colours. It is also important that co2 turns on 30 minutes to an hour before the lights turn on the make sure there are adequate levels of co2 for the plants when the lights turn on.

Diffuser flow:

If you do decide to a diffuser, you want to have a circular flow across your tank to make sure you have even co2 levels across your tank. The photo I put below will show a good example of how the flow of your tank can be to ensure good circulation of co2. It came from here.

 

I had seen mentions of inline and reactors here and there..I will have to do more research on those. Thanks so much for the info!

[Mmiller2001]

For a 75 gallon, I highly recommend a Cerges reactor. You will find that it's a bit more challenging the other ways. As @Sumson has mentioned, those methods are okay, but measuring pH drop seems to be the most accurate way to measure CO2. You want a 1 to 1.5pH drop from degassed to gassed. So you will take a sample of water from your tank, let it sit for 48 hours then pH it. That is your degassed pH. Next, take a water sample after CO2 has been on for about 2 hours, pH it. That is your gassed pH. You will want to measure a difference of about 1 to 1.5pH. 

I would start slow, around 3 BPS, after 30 minutes, take a pH. Then double the BPS and check again in 30 minutes. Repeat as necessary. When you get close to a 1pH drop, start watching the fish. Increase CO2 a bit slower and watch the fish. If they start sipping the surface, you've gone too far. Just back it down a bit and you should be on target. 

Here's a great resource for CO2 101.

https://www.2hraquarist.com/blogs/choosing-co2-why

The biggest mistake people make is they don't push enough gas out of fear. Just take your time and get it right, it makes a big difference.

 

Edited December 20, 2021 by Mmiller2001

[EVoyager31]

On 12/19/2021 at 9:03 PM, Mmiller2001 said:

For a 75 gallon, I highly recommend a Cerges reactor. You will find the it's a bit more challenging the other diffuser ways. As @Sumson has mentioned, those methods are okay, but measuring pH drop seems to be the most accurate way to measure CO2. You want a 1 to 1.5pH drop from degassed to gassed. So  you will take a sample of water from your tank, let it sit for 48 hours. Then pH it, that is your degassed pH. The you will take a water sample after CO2 has been on for about 2 hours. Then pH it. That is your gassed pH. you will want to measure a difference of about 1 to 1.5pH. 

I would start slow, around 3 BPS, after 30 minutes, take a pH. Then double the BPS and check again in 30 minutes. repeat as necessary. When you get close to a 1pH drop, start watching the fish. Increase CO2 a bit slower and watch the fish. If they start sipping the surface, you've gone too far. Just back it down a bit and you should be on target. 

Here's a great resource for CO2 101.

https://www.2hraquarist.com/blogs/choosing-co2-why

The biggest mistake people make is they don't push enough gas out of fear. Just take your time and get it right, it makes a big difference.

 

Thank you! That explanation was helpful. I ordered an inline diffuser that seems simple enough to get going so I am hoping for the best there. 

[Mmiller2001]

On 12/19/2021 at 7:12 PM, EVoyager31 said:

Thank you! That explanation was helpful. I ordered an inline diffuser that seems simple enough to get going so I am hoping for the best there. 

It will get the job done. You just waste a bit of CO2. No biggie. That's what I started with as well. 

[EVoyager31]

On 12/19/2021 at 9:17 PM, Mmiller2001 said:

It will get the job done. You just waste a bit of CO2. No biggie. That's what I started with as well. 

True, hopefully I will get a raise soon and will try out the reactor you mentioned! 

[EVoyager31]

On 12/19/2021 at 9:03 PM, Mmiller2001 said:

For a 75 gallon, I highly recommend a Cerges reactor. You will find that it's a bit more challenging the other ways. As @Sumson has mentioned, those methods are okay, but measuring pH drop seems to be the most accurate way to measure CO2. You want a 1 to 1.5pH drop from degassed to gassed. So you will take a sample of water from your tank, let it sit for 48 hours then pH it. That is your degassed pH. Next, take a water sample after CO2 has been on for about 2 hours, pH it. That is your gassed pH. You will want to measure a difference of about 1 to 1.5pH. 

I would start slow, around 3 BPS, after 30 minutes, take a pH. Then double the BPS and check again in 30 minutes. Repeat as necessary. When you get close to a 1pH drop, start watching the fish. Increase CO2 a bit slower and watch the fish. If they start sipping the surface, you've gone too far. Just back it down a bit and you should be on target. 

Here's a great resource for CO2 101.

https://www.2hraquarist.com/blogs/choosing-co2-why

The biggest mistake people make is they don't push enough gas out of fear. Just take your time and get it right, it makes a big difference.

 

Followup question for you: I did get an inline diffuser but I’ve been reading that surface agitation will work against me when adding c02. If I add the inline diffuser and it feeds into a spray bar outtake (that generally agitates the water a good deal) would I still be ok?

[Mmiller2001]

On 12/23/2021 at 11:46 AM, EVoyager31 said:

Followup question for you: I did get an inline diffuser but I’ve been reading that surface agitation will work against me when adding c02. If I add the inline diffuser and it feeds into a spray bar outtake (that generally agitates the water a good deal) would I still be ok?

100%, you want to have excellent agitation. You want gaseous exchange to occur rapidly. O2 and CO2 are independent of each other. You want to maximize O2 and CO2, by off gassing CO2 at a rapid rate. You will have to refill your tank more often, but CO2 is cheap.

https://www.2hraquarist.com/blogs/choosing-co2-why/how-to-push-the-limits-of-co2-safely

[Sumson]

@Mmiller2001 Is correct about the co2 and o2. Without good gas exchange this can also end up gassing your livestock in your tank so it is important to have good surface agitation when injecting co2.

[EVoyager31]

On 12/23/2021 at 2:01 PM, Sumson said:

@Mmiller2001 Is correct about the co2 and o2. Without good gas exchange this can also end up gassing your livestock in your tank so it is important to have good surface agitation when injecting co2.

Also I have a fairly tight fitting lid, this won’t be a problem right?

[Sumson]

Nope! I believe it will be fine with a tight fitting lid.

[Mmiller2001]

On 12/23/2021 at 12:03 PM, EVoyager31 said:

Also I have a fairly tight fitting lid, this won’t be a problem right?

I would have some space to let atmosphere in. Say 1 inch along the back?

[EVoyager31]

On 12/23/2021 at 2:28 PM, Mmiller2001 said:

I would have some space to let atmosphere in. Say 1 inch along the back?

Done and done. Now, one more question (because google and the links you provided seem to be talking about it at a level my pea brain can’t quite understand).

I did have a Ph drop once I got the c02 going.. from about 6.8ph down to about 6-6.4. I have some juvenile Rainbow fish that need a slightly higher ph.. should I be compensating by raising the Ph to a point that, once it drops, it will be in the desired range? If so, how can I raise it carefully to not give them ph shock, and how long will they be OK until stores open back up after xmas? 
my other tank parameters are good to go, Kh was 3 drops (from my understanding— 53.7ppm kh).

On 12/25/2021 at 1:32 PM, EVoyager31 said:

Done and done. Now, one more question (because google and the links you provided seem to be talking about it at a level my pea brain can’t quite understand).

I did have a Ph drop once I got the c02 going.. from about 6.8ph down to about 6-6.4. I have some juvenile Rainbow fish that need a slightly higher ph.. should I be compensating by raising the Ph to a point that, once it drops, it will be in the desired range? If so, how can I raise it carefully to not give them ph shock, and how long will they be OK until stores open back up after xmas? 
my other tank parameters are good to go, Kh was 3 drops (from my understanding— 53.7ppm kh).

P.s. fish seem to be ok right now. No gasping or odd behavior

[Mmiller2001]

On 12/25/2021 at 11:32 AM, EVoyager31 said:

Done and done. Now, one more question (because google and the links you provided seem to be talking about it at a level my pea brain can’t quite understand).

I did have a Ph drop once I got the c02 going.. from about 6.8ph down to about 6-6.4. I have some juvenile Rainbow fish that need a slightly higher ph.. should I be compensating by raising the Ph to a point that, once it drops, it will be in the desired range? If so, how can I raise it carefully to not give them ph shock, and how long will they be OK until stores open back up after xmas? 
my other tank parameters are good to go, Kh was 3 drops (from my understanding— 53.7ppm kh).

P.s. fish seem to be ok right now. No gasping or odd behavior

I would not be concerned about the pH and rainbows. This tank is Greggz's tank. It's full of rainbows and his pH is around 4.8. If your pH was 6.8, you want an injected pH around 5.8 to 5.3.

If you want to read his journal, and you should, here's where you can do that. It's the main source I used to achieve my own tank. The things you will read will conflict with alot of bad advice that continues to get passed down as facts and will definitely improve your own tank.

https://www.plantedtank.net/threads/greggz-120g-rainbow-fish-tank-scapecrunch-interview-1-18-2021.1020497/