• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Am I gassing my fish with CO2?

Jafooli

Jafooli

Member
Joined
21 May 2013
Messages
231
Location
Kent
Hi

I am injecting my CO2 via a in tank ceramic diffuser, I'm now cleaning it each week and its producing a fine mist. The whole tank looks fizzy now, I'm even now getting a film of CO2 bubbles on the surface, which is odd as I do have good surface agitation.

My tank is 200 litres, low light I presume, moderately planted, I'm just waiting for the plants to take off properly as there all quite small still.

So the problem is around the last 2-3 hours of the photoperiod my fish start acting strange, they either hide in a corner, or they seem to stay in one spot and just gasp, there mouths move rapid, its not natural behaviour I can see there obviously having problems breathing right. I know how to fix the problem, I just turn CO2 down... but I have never ever achieved a green drop checker in this tank and after going through a brown diatom mess I am now concentrating on flow and most importantly CO2 which is now why I'm facing this issue again. My safe level for the fish is 1BPS. When I go to 1.3 or 1.5 my fish don't like it. I guess different ppm levels can be more toxic to fish in different tanks as there are many things that play a role? so maybe using the green drop checker as a guide is not a good guide for me, until my plants spread out more, then maybe I should try to increase.

Is it worse to have CO2 bubbles everywhere in a tank? aka do the fish struggle more because its not dissolved and the bubbles are more concentrated? Someone please help me with that question as I'm paranoid.

I know many people on here use inline so maybe its more safe for the fish as the bubbles have dissolved before it reaches the output, and there for the CO2 is now dissolved so its not covering the fish in loads of concentrated CO2 bubbles.

I've always had this problem since the beginning of my tank, its been planted differently at certain times but always been a issue. when I had a 90l my drop checker was always green at 1BPS. 2BPS on this 200l, my fish would die, I've already lost some fish to this and enough is enough now, that's why I'm thinking of just using liquid carbon instead.

I've also tried the diffuser in my filter, I see quite a lot of CO2 was getting trapped, and all night the filters were making a noise, also the fish still acted strange with that method. ( 2x internal filters )

I'm sure I read 30ppm of CO2 is safe for fish and inhabitants, so if my drop checker is still a light blue and not green, but yet my fish act odd, and Its still blue, something is either wrong with my drop checker, or the co2 bubbles are more deadly to fish, or my plants are not big enough to produce enough oxygen to keep a balance in the tank.

I'm also using a pre mixed 4dkh solution which use to work great on my old tank, so I think its the real stuff. Hope someone can just let me know on why I'm having this problem.
 
Last edited:
I've never used drop checker or bubble counter...

I use pH profile relative to degassed pH. Pearling plants and fish distress are then the two markers to look for, again this is all done on a day when you can monitor the injection.

Fundamentally don't let bps / dropchecker override your observations that you are causing discomfort

Try a pH spot check of the water before injection and then throughout until gas off.

at the end of the day, how are the plants / algae?
 
Cheers for the reply,

I've just come through a bad time with diatoms, but I've never had any kind of algae outbreak before and most plants seem to have thrived in the past.

I still need to get a digital ph reader, which will probably be around a month away. But at least for now I can take some of your advice and go by observations and not worry as much, as its very stressful. I don't understand why my fish are acting like that even though its not green. I've never read anything about someone in the same situation as me so its odd.

My only guess is the CO2 bubbles from the diffuser effect the fish much more than a tank with pure dissolved CO2 from an inline diffuser.

So I guess I will keep it at a safe level for now, I might also turn my CO2 off an hour before lights out. I presume two hours might be to much.

Thanks again its just annoying as I need some kind of idea what my CO2 levels are and have no clue why my fish are stressed under a blue drop checker, I guess it will have to wait till I get a PH reader. Even then if my CO2 is low Its not like I could adjust it as the fish cant handle it. I will keep monitoring plants and lets hope there getting enough other wise I might change to liquid carbon, but I don't want to give up as pressurized CO2 is meant to be much better and I don't want to use both as I might be wasting money on fire extinguishers for nothing.

Thanks again.
 
if your fish are struggling with the amount of co2 then (first off reduce injection then) increase surface movement to ensure adequate gas exchange, its quite possible that once you start to raise the co2 levels again you will end injecting more co2 than your are now to find a balance where the livestock and plants are both happy.

I always think of it as there are 3 elements to co2 injection - how much (and how) you put in the tank, how its moved around the tank and how much surface movement you have. Change any of the 3 and it will have consequences to the concentration of co2 and o2 in the tank, ergo, consequences to livestock and plants.

Im prepared to be corrected here but, co2 and o2 dont inhabit the same space, if you have low o2 then any amount of co2 will just make life intolerable for livestock, equally its possible to have pretty high co2 levels and happy livestock as long as O2 is also high.

The livestock health is always the priority though, observing your fish and plants will always tell you more than a DC which is just a rough guide.
Try putting the DC right over the diffuser, if it doesnt change then the reagent is likely knackered.
 
Thanks Iain

That explains quite a lot, I also think you are correct regarding CO2 and O2.
At least I have some new ideas to try now. First I will try your method with the DC just to see what happens.

My surface agitation is quite high but I guess I can try and find the limit before it starts to break the surface, and then like you say I may find my self injecting more CO2, I presume because of the quicker gassing off, but at least I will get higher oxygen levels and hopefully find that balance. I may try all of this once I get a ph reader as It will give me more of a picture to whats really going on. For now I will monitor plants and keep CO2 in the safe zone.

My plants are not very large at the moment so I'm considering lowering my photoperiod from 9 hours to 8 and CO2 to turn off an hour before lights out. That will be a total of 2 hours less CO2 injection so that should help for the mean time and to be extra safe even with my CO2 in the safe zone I don't want to risk my fish suffering anymore.

Thanks again for helping.
 
Last edited:
I agree with Iain, this looks like an oxygen problem not a CO2 problem.
1-2 bps in a 200l tank is very unlikely to be enough to reach 30ppm (or whatever your desired level is ). In PFK recently George Farmer suggested about 1bps per 50l water as a ball park figure, and that seems about right in my experience.
I think your drop checker is telling the truth, you do not have a lot of CO2 in the water. You can confirm this with pH readings if you like but both will tell you the same thing.
However CO2 will reduce the ability of the fish to take up oxygen, and this could be what is happening. So with better oxygen levels you should be able To add more co2, getting up to a conventional amount. Of course it is a good idea to have good oxygen levels anyway, not just to enable us to inject CO2!
Note that CO2 has no effect on the oxygen level in the tank, it just affects the ability of fish to use oxygen, and if the O2 level is marginal then increasing CO2 could tip them over.
The usual sign of hypoxia is gasping at the surface but clinical signs are always variable.
 
Cheers Spnl

I have raised my internal filters a bit more, which has slightly increased surface agitation as I already have a lot, if I go any higher my outlet's will be sticking out the water, how much surface agitation is to much?
I've never once witnessed any fish gasp at the surface, but what I do witness is unusual behaviour, restlessness, fish hiding in corner, gasping - not at the surface though, just a total behaviour change compared to there normal behaviour which is mostly occurring in the last couple of hours. When I've lost a couple of fish in the past due to CO2, what I believe was CO2 is the fish seems to lose its ability to swim straight, it either swims on its side, upside down, or just loses the ability to swim at all and just floats around in the current until it lands somewhere, then just breaths rapidly. I guess its a bit like swim bladder, but the reason I think its because of CO2, is this has only happened when I've raised BPS and then inspected the other fish in the tank to see there in stress. The next day with low CO2, all fish are fine again, and no rapid breathing etc, all doing there own thing out in the open.

Does what I described above sound like CO2 toxicity? or another issue? like I say it only happens when I've had high CO2 levels this is why I've not gave it a second thought, unless there is something else in my water attacking my weaker fish leading to swim bladder, but then again 50% water change each week and a clean tank, I just don't know any more. As for now I will focus on getting oxygen in the tank but I can't do much more than what I already have and at 1BPS of CO2, compared to what you said above about what George Farmer suggests, that's around 4BPS in a 200l, it seems like this could be quite challenging, which makes it even more bizarre to why my fish act odd.
 
Jafooli said:
Is it worse to have CO2 bubbles everywhere in a tank? aka do the fish struggle more because its not dissolved and the bubbles are more concentrated? Someone please help me with that question as I'm paranoid.
Click to expand...
Jafooli, you're running around in circles. Just turn the gas off 2-3 hours earlier than you are doing now. Why make things more complicated?

Cheers,
 
Thanks for your reply Clive

I was just concerned that the bubbles may be higher concentrated then pre dissolved CO2 from an inline diffuser, there for effecting the fish to breath efficiently.

I will turn gas off 2 hours before, is not 3 hours a bit to much? that would cause fluctuation which could lead to algae? I know I cant exactly start monitoring my CO2 levels until I get a PH reader, but I thought I could at least get a higher bubble rate then 1BPS, and I also believe my distribution of CO2 is great. My whole tank is covered in a CO2 mist, reaching all areas of my tank.

Hmm the more I do research on swim bladder the more it seems that was the cause of the deaths, I did have a khuli loach also die about a week ago with a large lump in its body, which also is a symptom of swim bladder.

I just cant understand why these problems only occur when I raise CO2, its as if the high CO2 is stressing the fish then maybe its leading to swim bladder, how can I eliminate any nasties in my water which may be attacking my fish. I looked at a product for swim bladder, but I've read a lot on here about water changes are key.... so how many water changes would I need to remove any nasties or lower there levels.

I think for now I will just keep CO2 low, buy some liquid carbon from Aqua Essentials, I presume there own carbon is as good as any, and when I get a digital PH meter and record my own PH profile then I can start with the increasing etc, but hope someone can just answer me about the best way of removing any bacterial or parasites that might be in my tank effecting my fish, I presume there always there, but they may be in high numbers, and also regarding turning CO2 off 3 hours before, as I don't want BBA etc.
 
Last edited:
What you described from the past does sound like CO2 toxicity.
Co2 has several effects. Firstly it stimulates respiration (at least it does in land animals and I assume that is the cause of the more rapid gill movements seen in fish).
It will cause acidosis, akin to respiratory acidosis in mammals, and this could lead to hypoxia if O2 is not good.
Thirdly CO2 is an anaesthetic. At higher levels the fish will start to lose conciseness, which I guess is what happened to your fish. And of course this explains why they generally recover so well.
Exactly what signs the fish show will depend on the combination of factors, including temperature. Low pH will also make CO2 have more direct toxic/anaesthetic effect, as it increases the proportion that is found as dissolved gas, as opposed to bicarbonate which is much safer for fish. But that is unlikely to be a significant at usual pH levels (6 to 7 ish).
Yours does sound like a really odd problem. I wish I could get high CO2 levels with a few bubbles per second!!
 
Hi Spnl

It seems this problem is odd, I'm now stuck in two worlds, I know for a fact all these problems are happening when I try to increase CO2.
The rapid gill movements and gasping from there mouths is the number one symptom and effects all fish in the tank.

My PH from my tap is 8, when left 24 hours over night, and in my tank its 8, but with CO2 injection that obviously changes. When I purchased 4 Panda Cory's one died 24 hours later, I got a replacement at the shop and they tested my water, the guy said it was because my PH was 7 and not 8, all there tropical tanks are at 8 and I had to explain well I use CO2, bla bla, he was not a nice guy to deal with lol.... as he was convinced to try and find some kind of problem. So on that day I obviously had a drop of 1 PH, and I have really high KH.

I noticed my clown loach yesterday swimming on its side for a few seconds, and then returning back to normal, a few days prior to this when I tried to increase CO2, my clown loaches never came out there ornament once, and other fish were acting odd again at night. I've since turned it down, and then made this thread. As Clive knows I had deficiency problems because of an increase in CO2, I've solved them for now, and am now trying to increase CO2 again so this is why I'm facing this. Sorry if it sounds like I'm putting my fish through hell, but that's why I made this post so I can understand what's happening. I'm not sure if its because of all the CO2 mist everywhere as I'm sure I read swim bladder can be also caused when gas becomes trapped, I think there referring to oxygen bubbles though and not CO2.

Like mentioned above I will keep BPS low, and focus on oxygen, get some liquid carbon, wait till I get a digital PH reader then take it from there. But I don't think my CO2 is has high as what you think, as surely my drop checker would be green in all areas of my tank.
 
Last edited:
Jafooli said:
I will turn gas off 2 hours before, is not 3 hours a bit to much? that would cause fluctuation which could lead to algae? I know I cant exactly start monitoring my CO2 levels until I get a PH reader, but I thought I could at least get a higher bubble rate then 1BPS, and I also believe my distribution of CO2 is great. My whole tank is covered in a CO2 mist, reaching all areas of my tank.
Click to expand...

Yes, CO2 is the most toxic thing we add to the tank. This is no secret, and that's why it has to be managed . You don't need 8 hours of gas. CO2 is super duper important at the beginning of the photoperiod, but strange as it may seem, it's not very important near the end of the photoperiod. That's why most of the CO2 related problems are actually occurring in the morning. That's also why we advise to get that big pH drop by lights on.

Forget about all that other stuff. If you want to check to see if the symptoms of the fish is due to the CO2 then do a massive water change at the onset of symptoms and see if the symptoms disappear. If they do, then you have pretty good evidence that CO2 is contributing to the problem.

Cheers,
 
Jafooli said:
Hi Spnl

It seems this problem is odd, I'm now stuck in two worlds, I know for a fact all these problems are happening when I try to increase CO2.
The rapid gill movements and gasping from there mouths is the number one symptom and effects all fish in the tank.

My PH from my tap is 8, when left 24 hours over night, and in my tank its 8, but with CO2 injection that obviously changes. When I purchased 4 Panda Cory's one died 24 hours later, I got a replacement at the shop and they tested my water, the guy said it was because my PH was 7 and not 8, all there tropical tanks are at 8 and I had to explain well I use CO2, bla bla, he was not a nice guy to deal with lol.... as he was convinced to try and find some kind of problem. So on that day I obviously had a drop of 1 PH, and I have really high KH.

I noticed my clown loach yesterday swimming on its side for a few seconds, and then returning back to normal, a few days prior to this when I tried to increase CO2, my clown loaches never came out there ornament once, and other fish were acting odd again at night. I've since turned it down, and then made this thread. As Clive knows I had deficiency problems because of an increase in CO2, I've solved them for now, and am now trying to increase CO2 again so this is why I'm facing this. Sorry if it sounds like I'm putting my fish through hell, but that's why I made this post as I can understand what's happening. I'm not sure if its because of all the CO2 mist everywhere as I'm sure I read swim bladder can be also caused when gas becomes trapped, I think there referring to oxygen bubbles though and not CO2.

Like mentioned above I will keep BPS low, and focus on oxygen, get some liquid carbon, wait till I get a digital PH reader then take it from there. But I don't think my CO2 is has high as what you think, as surely my drop checker would be green in all areas of my tank.
Click to expand...
Tbh the guy is full of s!!t if he was keeping Corries responsibly his ph would be much lower than 8 lol, as Clive states co2 is most important at lights on in my 90cm I have to have it on 3hrs before lights but it goes off 3 hours before lights too, play around with injection rate timing etc until you find an equilibrium for plants and fish.
 
Cheers for the replies,

I've learnt something new, I didn't know people turned there CO2 of so early, the earliest I've read from other threads on here is a hour before, and I just presumed that was because the CO2 will last at a high enough level for the last hour. So glad I now know that, as every little bit of knowledge helps.

Is there a possibility that the CO2 gas is getting trapped in the fish, then causing swim bladder like symptoms? as I read that's how swim bladder can also happen, from trapped oxygen. In this case it would be trapped CO2, it would explain all the symptoms if it was CO2 toxicity and then the swim problems due to the trapped CO2 bubbles from there rapid gasping.

Yeah Tim he was, and I had spent weeks trying to get hold of Panda Corys, and they said on the phone they had some come in, I went straight up there in the morning and to my surprise there were over a few hundred in the small tank. They were tiny though, but they all seemed healthy and active. Next day one had died, went back with my water and the dead fish in the bag as they wanted evidence. He was trying to explain to me, its a common problem and its normally due to ammonia of a tank that fish die, and bla bla, he then read each result in front of me as if he was going to catch me out, and he looked real shocked when all my readings were great, then when he read the PH 7 he went off on one, saying yeah that's why, I don't know how your tank has that we keep all our fish at 8 bla bla, (even though PH fluctuation from CO2 don't effect the fish I believe) and when we went over to the tank to get my replacement there were quite a few dead ones in there, so it wasn't just mine that died. I didn't have the nerve to speak up but he gave me another lecture while holding the bag in the air with the replacement cory and he said you can clearly see this is one healthy active cory so if it dies we can't offer you a guarantee no more. Either he was having a bad day or he didn't like me. I wasn't sure about even putting the new cory in my tank, but I did and this was many many months ago and all my fish have been fine thank god, but I seem to find many people at fish shops seem to think they know everything, and I always overhear information that's not correct and quite shocking.

Thanks again for everyone's help.
 
Last edited:
You will find lfs will try to baffle you with bulls!!t constantly, I like to do it back to them :) seriously fish is a good point of call for species research mate, ime even if you have a semi thriving planted tank you'll give your fish a better environment than the lfs tank they came from, always acclimatise them slowly I use the drip method for fish and shrimps and that works for me, get the co2 in before lights on and the plants will provide oxygen for themselves and livestock, try not to have too much residual co2 at the end of the photoperiod whether through surface agitation or good timing management, it's all a learning curve mate, everyday is a school day :)
 
lol I would pay to see Clive in a fish shop when they try to sell him a nitrate test kit or when they go on about some other rubbish, I wonder if he just goes along with it. :lol:
If I had the confidence like you, I would be like yeah I got a new fire extinguisher yesterday, and my CO2 system is all up and running so need some plants. Also any chance you some potassium nitrate laying about, need those nitrates! I Would love to see there reactions.

Cheers again.
 
  • Like
Reactions: tim
ceg4048 said:
You don't need 8 hours of gas
Click to expand...

My CO2 comes on at 9 and now goes of at 5. I did not reduce my photoperiod in the end.

So the CO2 is now going off 3 hours before lights out! , so you mention I don't need 8 hours of gas, but how did you work this out? Can I switch it off even more earlier than 3 hours? lets say 6 hours of CO2, that would be switching CO2 off at 3. For me that would be great, my fish don't suffer around that time, so if you can let me know Clive if that's ok that would be great, and if I do switch it of 5 hours before, what signs do I need to look for with the plants encase its a problem, I have no idea how you worked it out. I'm sure some people keep there lights on for 12 hours, so 8 hours of CO2, would mean 4 hours without, and if they switched it off more earlier, the tank would go hours with out CO2 being injected. Do plants take less CO2 during the day compared to the first 1-2 hours when lights come on?

Would be interesting to know, with out it becoming complicated, but hope you can let me know, as I can't really see my surface agitation improving any more. Today the fish seemed fine so seems good, but if I can go back another hour, would be great., especially as I'm still injecting at 8 hours so thought I would ask.
 
Well it's very difficult to work out exactly what to do from afar. The only thing you have to concentrate on is that if you are going to have only 5 hours of CO2 in 8 hours of light then the CO2 in those 5 hours must be excellent and it must occur at the front end, not at the back end or in the middle. You have injection rate, surface agitation and timing as parameters to work with and this assumes that your distribution method as well as gas diffusion methods are also excellent.

From a practical standpoint, turning the gas on 5 hours before the lights is not a very good solution. You know, more or less what kind of pH drop you need so use the other two parameters in any combination in order to drop the pH to the desired value by lights on. I cannot tell you what bubble rate to use. You have to experiment with that.

Ideally, it would only require about an hour of gas injection to saturate the water with CO2 and to drop the pH the target amount by the time the lights come on. However, if that injection rate continues for 5 hours it may make the fish uncomfortable. You may have to reduce the injection rate and settle for a smaller pH drop so that you don't gas the fish, or you can make minor adjustments to the timing so that instead of 1 hour, you turn the gas on 1.5 hours prior, with a smaller injection rate. Or you may use a bit more surface agitation to moderate the gas concentration buildup.

This difficulty in zooming in on the correct injection technique is the origin of my rants against people who are in such a hurry to add fish to the tank. It leads them on a path to do silly things to accelerate the cycling of the tanks because they just can't wait to dump fish into the tank. Then they have these problems and the presence of the fish handcuffs them.

So, the fact that you have fish will make it very difficult to figure out the best combination of bubble rate, timing and agitation that satisfies both the plants and the fish. Here is a sample routine that Houdini might use:
1. You need to be able to measure the pH.
2. You need to be home during the photoperiod in order to monitor the health of the fish.
3. Choose an injection rate and turn the gas on 1 hour prior to lights on.
3a. Do not ask other people what injection rate they use. Their tank is not your tank. Their answer will be irrelevant.
YOU select the initial rate based on your previous observations of how the gas behaves in your tank.
4. Compare the pH drop after 1 hour to your target pH drop.
4a. If the pH drop meets your target, then monitor the fish behavior during the rest of the photoperiod.
4a1. If signs of toxicity is detected within the first 1/3rd of the photoperiod then this indicates the injection rate is excessive.
4a2. The pH measurement should confirm this as the value will fall below your target.
4b. If the pH drop exceeds the target then the injection rate will most likely be excessive.
4c. If the pH drop does not meet target then this indicates either the injection rate is too low or the agitation is excessive.
5. Based on the results of step 4, the next day make adjustments to the timing, agitation and injection rate and repeat step 4.
6. If you run out of time by which you can monitor the tank you always have the option of turning off the lights and CO2 until you have the time to monitor. This keeps the fish safe, saves gas and reduces the stress on the plants.
If it's a week before you have time again, remember that the CO2 would have completely off-gassed during that time (which does not happen with the daily CO2 injection cycle) so that when you start this sequence again the pH drop won't be as much as it was previously. Don't overreact to this. Keep records and be systematic in your approach. Make minor adjustments based on the previous results.

Cheers,
 
You must log in or register to reply here.
Back
Top