Unexpected
Well-known Member
I have one recent fish addition who seems to be sensitive to CO2 at the 1 to 1.5 pH drop. Will I run into problems if I reduce my CO2, maybe into the 20ppm range?
30ppm CO2 vs 20ppm CO2
- Thread starter Unexpected
- Start date
- Tagged users None
Mr.Shenanagins
Well-known Member
I had a similar issue with my Praecox rainbows, first time I experienced that. Can you increase agitation to increase gas exchange?
Unexpected
Well-known Member
- Thread starter
- #3
It’s pretty close to as much as the returns will produce. All fish stress out at a pH of 4,97 and I lowered CO2 to 5.19. She’s doing well there.
Here’s a video of the agitation.
Freshflora
Active Member
I’d say to lower your injection rate just a bit to where they’re all comfortable, if that’s 5.19 then stay there. Then reevaluate plant health/algae in like 1-2 weeks. If you have any issues, you may have to add an additional skimmer or powerhead to increase your surface agitation to be able to raise CO2 up a bit again like @Mr.Shenanagins suggested.
Unexpected
Well-known Member
- Thread starter
- #5
Will do. I went ahead and angled the returns to basically create rapids at the surface. CO2 is cheap and if I go through a bottle a few weeks sooner, so be it. I’ll give her a few more days and then increase very slowly while watching the plants.
Plants will find it more difficult to adapt to reducing CO2 ppm (need to build more Rubisco, this is an expensive process for them) than to increased CO2 ppm. My personal experience is that some plants suffer, and adaptation can take 2-3 weeks with sensitive plants stunting or worse. I am not a plant expert, but believe science (@plantbrain ?) confirms this.
Plants 'suffering', especially when the tank is not optimally maintained, could be a potential cause for algae to seize their opportunity?
I experimented a lot with CO2, got plants suffering or dying but miraculously never too much BBA. I suspect the reason was that I maintain my tank well - pruning, cleaning and regular water change.
Unexpected
Well-known Member
- Thread starter
- #7
Is there a known amount of CO2 per point of Ph drop? If my fish stress at pH 5.0 ( 30ppm ), what amounts of CO2 is a pH of 5.2?
The relationship is logarithmic, this is the famous pH/kH/CO2 ppm table. This table is much criticised, but it is the best we have.
When increasing pH by 0.2 you will get about 63% of the CO2 PPM. In your case perhaps around 20 ppm, if you came from 30 ppm.
There is a lot of theoretical debate, and criticism, about measuring or calculating CO2 ppm. One might argue that this debate is partially irrelevant when we realise that stability is more important than the absolute value. So why worry too much about giving a number to the PPM? Key is to keep it stable, observe plant health and live stock and adjust when needed to a new stable level - whatever the ppm's is.
Last edited:
Mr.Shenanagins
Well-known Member
@Yugang I could have sworn I’ve read a post by Tom before that lower levels of CO2 can still be successful? Granted it’s being delivered efficiently and is remaining constant throughout the day.
I just re-read your last post and you basically said the same thing, consistency and stability. My bad, I’m a few beers in
I just re-read your last post and you basically said the same thing, consistency and stability. My bad, I’m a few beers in
I must admit, I am heavily influenced by Tom Barr, so there is no coincidence here@Yugang I could have sworn I’ve read a post by Tom before that lower levels of CO2 can still be successful? Granted it’s being delivered efficiently and is remaining constant throughout the day.
I just re-read your last post and you basically said the same thing, consistency and stability. My bad, I’m a few beers in
Tom is one of the very few who have a deep scientific background (also the professors where he did his PhD, with really interesting research on aquatic plants), as well as a lot of practical experience (his own tanks, his customers and friends tanks) to validate assumptions. In my personal opinion he is one of the greats in the hobby, at comparable level to Amano in terms of his contributions. Just wish he would post a bit more, as I am sure also Tom has built new insights over the past decade.
Sternla
Community Member
Since you are running kh 0, what if you raised kh to 1 and see how the fish behave after running the c02 as is.
Freshflora
Active Member
That wouldn’t change the CO2 ppm by itself. You can’t adjust the amount of CO2 just by changing the KH, only by adjusting the injection rate of the CO2. Thinking you can change the CO2 ppm only by adjusting the KH comes from a misunderstanding of the KH PH CO2 chart/relationship.
Sternla
Community Member
Do you think it is the ppm c02 or the ph that you get to when you are at 30ppm that’s effecting the fish? If it’s the ph then raising the kh would shift ph up.
Unexpected
Well-known Member
- Thread starter
- #14
It was the CO2, the one fish was sipping the surface when all the other fish were acting normal. I think she may have some gill damage from being shipped to my local fish store. Luckily, the store is letting me swap her for another. The male I bought along with her does not struggle. Which is a good thing because he is quite colorful.
GreggZ
Moderator
Nice looking Goyder River!
With my tank of Rainbows I start to notice a change at anything past a 1.4 drop. And that is with LOTS of surface agitation. Even before they head to surface they just seem to slow down and become lethargic.
So if they start reacting at a 1.5 drop, just slowly dial it back until you hit a good point. Plants will be fine. That is still loads of CO2.
And don't be too concerned about the CO2 ppm. You will never know what it truly is without expensive test equipment. The calculators say mine is about 100 ppm CO2. Is that true? Unlikely but I don't care I just want to optimize CO2 to a level just a bit lower than a level that would bring on symptoms/stress.
Unexpected
Well-known Member
- Thread starter
- #16
If 4.97 was the stress point for all fish, where would you back off to?
GreggZ
Moderator
Are you using a controller? If so it's easy to dial in. Go to 5.02 and observe for a day or two. If still showing signs then back off to 5.07. And so on. At some point you reach a level where both fish and plants are happy.
If not using a controller it's a bit more difficult as you need to fine tune either the needle valve or flow meter, whichever one you are using. This is a bit less precise and takes more time/skill to really dial it in. Needle valves can be touchy and hard to change in small increments. Flow meters are a bit easier. A controller is the easiest but you must have stable dKH for them to work well.
Hope that helps.
Unexpected
Well-known Member
- Thread starter
- #18
I am. And thank you.
Bumping this thread, but now with the knowledge that @Unexpected tank has gained a bit of celebrity status as an award winner.
@Unexpected , have you indeed settled for a 1.0 pH drop for the tank that worked so well for you? From your article ("tank of the month") it is not clear what your degassed pH reference is?
We have the thread what do you spend most money on , and for most it is electricity and/or CO2. I am still fascinated what is really the rationale of optimising the tank with high CO2 injections (1.2 ... 1.4 ... and more), compared to 1.0 (assuming balanced with light PAR and all the rest) also in relation to the posts in CO2 Best practices, unknowns and myths
@Unexpected , have you indeed settled for a 1.0 pH drop for the tank that worked so well for you? From your article ("tank of the month") it is not clear what your degassed pH reference is?
We have the thread what do you spend most money on , and for most it is electricity and/or CO2. I am still fascinated what is really the rationale of optimising the tank with high CO2 injections (1.2 ... 1.4 ... and more), compared to 1.0 (assuming balanced with light PAR and all the rest) also in relation to the posts in CO2 Best practices, unknowns and myths
@GreggZ , what flow meter are you using, and would you buy same again?
GreggZ
Moderator
Flow meters can become complicated. We are talking about measuring cubic centimeters per minute, which is a VERY small measurement of flow. So people many times make the mistake of buying something with the wrong scale.
I have been using a Dwyer flow meter for many years. When I first started talking about flow meters, people thought I was a little nuts. But to me it's easily a more elegant solution to regulating flow than counting bubbles.
The thing about the Dwyer units is that they are readily available and reliable. I use the RMA-151-SSV. It has a 5 to 50 cc/min scale. If it ever fails I would go with the the RMA-150-SSV which has a 10 to 100 cc/min scale. The reason is that in my 120G tank, I am running very close to 50 cc/min to achieve a 1.4 pH drop, so I don't have much room on the top end.
In general tanks under 90 gallons should go with the 151 model, and and over 90G should go with the 150 model.
I hope that helps.