co2 wonderings

[Da Squid]

Sorry for all the questions, but I'm trying to make sure I have a good grasp on all of this.

If one goes from no CO2 to a pressurized system at the optimal rate (around 30ppm?) wouldnt that cause a quick and drastic drop in PH? Or is there a gradual way that CO2 is meant to be introduced that doesnt shock the fish?

Also, in regards to the PH monitoring device (I know, I know. An unneccesary luxury ), do you wait until you see what the PH drops to after getting 30ppm before setting it? If this device is always changing the gas flow into the tank to keep the PH the same, couldnt that create uneven CO2 levels and breed BBA?

I have mostly low light plants in my tank now. Is it safe to upgrade my lights and get CO2 right away, or should I put some faster growing plants in there FIRST to help use all the carbon I'm introducing.

Am I putting too much thought into this? Haha..

 

[Robert H]

Yes, the more C02 you add to your water, the lower your pH goes. If you add it quickly, the pH falls quickly. If you do it slowly, it drops slowly. How much it drops or swings depends on the carbonate hardness of your water, how much of a buffer you have.

Generally speaking, start at one bubble every 2 or 3 seconds and raise it one bubble at a time over several hours until you reach the desired level. If you do it quickly, only the fish or other animals would be affected. Plants won't care. Fish may die from pH shock

 

[mgamer20o0]

If you do it quickly, only the fish or other animals would be affected. Plants won't care. Fish may die from pH shock

dont want to make it out to be everything you say is wrong so ill use a quote from a very respected plant person in the hobby.....

Acids, of are two main types, strong acids, HCL, HNO3, H2SO4 etc,
CO2 is a weak acid, the strong acids will break the bicarbonate up and release CO2 gas, produce heat etc.

Weak acids do nothing to the bicarbonate, the alkalinity(generally) fraction, sometimes called KH.

Fish respond poorly to rapid changes in the KH, this is due to osmoregulation, salts etc, CO2 is not a salt, has no impact of KH, while it may change the pH, the alkalinity remains constant.

If you think or believe this does any harm to fish, folks using CO2 gas do water changes with tap water lacking high CO2 every week and subject the fish to pH changes of .5 to 1 full unit in very short times frame and to date, no one has ever had any issues, we are talking thousands of planted tanks over decades..............

So.........what evidence does anyone have to the contrary is what I'd like to know because after 15 years of using CO2, I've yet to see a lick of evidence that anything to do with pH and CO2 is a problem. I've kept hard water Rift fish, Altums, Apisto's, Rainbows, you name it.

We add CO2 for one reason, to fertilize the plants, not to control pH.
The rules for pH are out the window once you start using CO2 to fertilize.
A fish might still prefer a higher or lower KH, but the pH is not important if you are using CO2 gas.

Regards,
Tom Barr

If one goes from no CO2 to a pressurized system at the optimal rate (around 30ppm?) wouldnt that cause a quick and drastic drop in PH? Or is there a gradual way that CO2 is meant to be introduced that doesnt shock the fish?

it takes a litle time for the co2 to build up. it not really shock you have to worry about just trying not to od too much co2. you start slowly to dial in the amount you need. since there is so many factors its hard to say how much co2 you need. one thing i suggest is investing in a drop checker. really the best way to visually tell how much co2 is in the water.

 

[marchmaxima]

The other reason you might want to add CO2 gradually is to observe the reaction of your plants.

If you are putting in sufficent nutrients & elements for them then CO2 will only boost growth. You find the balance by introducing CO2 at a small rate to start with. You should notice immediate sprouting & growth & colour depth. Then slowly increase the amount of CO2. You know you have too much when your plant's growth rate levels off & even though you are still increasing CO2 levels. When you notice this, you back off the CO2 to the amount you were putting in when you last noticed increasing plant growth & health.

But keep an eye on things closely when using CO2 for the first time. If you notice your fish gasping at the surface, then this is a sign you have way too much CO2 and not enough O2. Reduce the the CO2 immediatly and throw in an airstone to increase O2 for your fish. Hopefully it wouldn't get to that.

 

[mgamer20o0]

co2 and o2 for the most part are independent.

 

[marchmaxima]

true. I should have said that.

 

[jsoong]

I'll throw my 2 cents in:

I would agree that in general, pH changes from CO2 variations are well tolerated, so no need to get too obsessed about that. <People who turn the CO2 off at night have daily pH swings & fish handle that fine. Thsi has to do with physiology, respiratory vs metabolic acidosis.>

The amount of pH drop depends on your KH. Higher KH decreases the pH swing. Personally, I would aim for a reasonable KH to minimize the swings - even though I know that the pH swings aren't bad, it makes me feel better!

A pH controller varies the amount of gas injected based on your set pH. This helps keep the CO2 level in the tank constant! <Not the other way around.> Assuming that your buffer stays constant, the CO2 level is directly proportional to the pH difference (of your current pH & starting pH). By setting a constant pH, you are maintaining constant CO2 levels. The amount of gas injected varies based on use - ie if your plants are using more, it will put in more.

Solubility of CO2 & O2 are independent. ie. Adding more CO2 will not drive out O2. Very high CO2 is an anesthetic, so if your really overdose CO2, you will put your fishies to sleep & eventually kill them. <Happens in people too - "CO2 narcosis of the deep" is CO2 poisoning while diving. Also, CO2 is a humane way to euthanize animals.>

Low light plants don't benefit too much form CO2, but I don't think you will do damage. <Except to your pocket book!>

 

[rkilling1]

The amount of pH drop depends on your KH. Higher KH decreases the pH swing. Personally, I would aim for a reasonable KH to minimize the swings - even though I know that the pH swings aren't bad, it makes me feel better!

Sorry jsoong, but I have to point out that pH changes from adding CO2 are the same no matter how much your KH is.

If you have a KH of 1.0 and add to 30 PPM CO2, your pH will change by 1.0 pH unit. (7.0 to 6.0) If your KH was 15, adding 30 PPM CO2 would have the same 1.0 pH unit reduction. (8.0 to 7.0)

 

[Robert H]

Tom Barr seems to have a habit of coming out with things that are the total opposite of long standing wisdom. All I know is if you go to any fish club and talk to any breeder you will find they acclimate fish very carefully to water conditions. When I bought apistogrammas and other soft water fish from auctions, I was instructed to add a little bit of my tank water to the bag gradually over a period of two or three hours to avoid the fish from going into shock, not just from temperature, but pH.

Back in the early 90s, I killed my share of fish when I tried to add C02 to the level I wanted in just one day on two different occassions. When i spread it out over a couple a days, it never happened again, and thats how I have always done it since.

pH definetly has an affect on fish. In breeding the pH determins what sex the fry will be. pH induces spawning, can affect the immune system, respiration, and a number of other things.

 

[jsoong]

Sorry jsoong, but I have to point out that pH changes from adding CO2 are the same no matter how much your KH is.

If you have a KH of 1.0 and add to 30 PPM CO2, your pH will change by 1.0 pH unit. (7.0 to 6.0) If your KH was 15, adding 30 PPM CO2 would have the same 1.0 pH unit reduction. (8.0 to 7.0)

Yes, Rkilling, you are right, the pH will change the same amount for a given CO2! I stand corrected!

I did read somewhere that you need adequate KH to inject CO2, the reason given was that it moderates the pH change. Looking at the H_H equation, it is the Hydrogen concentration change that is moderated, not pH. Since pH is logarithmic, a pH change of 7 to 6 is a bigger change than 8 to 7. <The [H+] change in the former is 9x10^-7, the later 9x10^-8, or 10 times less change in the latter case.> I am not sure if this makes any difference to the fish. I think I am going to have to question if you need a certain KH to inject CO2.

 

[mgamer20o0]

Back in the early 90s, I killed my share of fish when I tried to add C02 to the level I wanted in just one day on two different occassions. When i spread it out over a couple a days, it never happened again, and thats how I have always done it since.

there 2 ways people do this which also leads me to believe it doesnt effect them or doesnt effect them much.

1st one is people who have the co2 on a timer which also use air pumps at night. there many people who turn it off at night. with the addition of the air pump over a couple hours the tank is surely gassed out. when the lights come back on the air pump turns off the co2 goes back on and the ph once again drops.

2nd one is people who leave the co2 on 24/7 when the lights go off the plants stop using it. then the ph goes down even farther. when the lights go back on the co2 levels drop with the ph going back up. with out a ph monitor this is happening all the time.

Back in the early 90s, I killed my share of fish when I tried to add C02 to the level I wanted in just one day on two different occassions. When i spread it out over a couple a days, it never happened again, and thats how I have always done it since.

quick guess would be you over loaded the tank with co2. doing it slow is more of a way to dial it in.

 

[Robert H]

Well i have never used air pumps, and most of the time I have always left it running 24/7 as the majority of hobbyists do. The number of hobbyists actually using a solenoid, and even more so a pH controller has always been in the minority.

Leaving it running at night is not a problem because the change in pH is gradual over a period of hours, as it is in the morning when the lights come on, but going from 0 ppm of c02 to 30 ppm of c02 in five minutes and having the pH drop that much in five minutes is a little different than a few hours. Shrimp are even more sensitive to pH than fish.

 

[Da Squid]

Thanks everyone! All this discussion is really helping me out and I'm taking notes . I'll be back to bug you with more questions as the week drags on.

 

[Orlando]

Fluctuations in PH from co2 are completely harmless. Its to much co2 and not enough O2 that is the problem.

I run more tanks than I can count on both hands and feet with pressurized co2. I have Altums,S.American Dwarf Cichlids all the small nano fish you see around and I have yet to see PH be an issue with them in regards to co2.

Right from the bag in to the tank, no acclimation. Maybe its my luck? But its worked for years. I use timers with solenoids and some tanks have controllers.
One thing I would not do is feed co2 24/7 without shutting off. Its a complete waste of co2 during the night cycle. Why feed co2 at night?
Co2 does not affect the Osmotic balance in fish.

Save co2 by using a timer. Its to easy to do and your fish will love you for it at night and save you money


Regards,
Orlando

 

[marchmaxima]

I would tend to agree with the last post. I picked up a reg with a solenoid just two weeks ago from ebay for $130 aussie dollars + postage. I'm not sure what the US costs are, but here regs (not the real el cheapo ones) start at $90AUS.

For me, it worth the couple of extra bucks up front which I will save in cylinder refills pretty quickly.