• 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
  • You can now follow UKAPS on Instagram.

More CO2 questions

Sacul

Member
Joined
10 Dec 2020
Messages
64
Location
Devon
Hello all!

After getting all excited about getting my new tank setup with CO2 and worrying about what equipment I need and so on I completely forgot about everything else which I should have asked first. Better late than never I guess!

Water changes
When are these best done in the day when injecting CO2? During the day when CO2 is on or evening when CO2 is off? Or something else?

Medications
Because of the tank move and introduction of CO2, new flow, ferts and everything else I've seen a bit of stress in the fish and noticed some fungus/fin rot show up, I have since moved these fish into quarantine and they are under treatment. Fingers crossed
The question is, can I treat my main tank with any type of medications the same way or does it effect the CO2 at all or anything I need to look out for?

New livestock
When the time comes to add some more livestock when is the best time to do so? Going from a bag with no CO2 to a fully gassed tank I would imagine could be stressful. Is there a rule of thumb for doing this?

I'm sure there are other questions but that's what has come to mind at the moment. Thanks guys for any help
 

Hufsa

Member
Joined
22 Aug 2019
Messages
1,344
Location
Norway
Ideally do water changes before the gas is due to come on or after the photoperiod (period the light is on). Its generally recommended to not disturb the CO2 levels while the plants are actively growing.
If its an emergency then of course you can water change whenever.

Medications wont affect CO2, however many medications use up oxygen when they are added to the tank. Its generally good practice to vigorously aerate or add an airstone while medicating a tank. Medicating isnt something you should have to do on a regular basis, so some disturbance to CO2 levels during treatment is acceptable.

Dont add new livestock to a tank with peak CO2 levels (30ppm or whatever you usually use).
Either add them after the CO2 levels have dropped for the day (so after photoperiod), or dont turn on CO2 the day you plan to add fish.
If youre very concerned about plant growth for the day without CO2, you can also leave the lights off.
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,362
Location
Thailand
When are these best done in the day when injecting CO2? During the day when CO2 is on or evening when CO2 is off? Or something else?
Ideally do water changes before the gas is due to come on or after the photoperiod (period the light is on). Its generally recommended to not disturb the CO2 levels while the plants are actively growing.
As with Johnny and Amber. Call for speculation, hersay 🥳
There is absolutely no problem in changing water even in the middle of the photo period when CO2 is full steam on. It is not CO2 fluctuation happening on a fix point in time but on the longer run that is problematic. Many people do WC during the day and have no issues whatsoever. I do it myself often too. I see no ill effect. No algae. No death. No nuclear explosion. Some even go to claim that it's beneficial, although I am not ready to make that claim. @Sacul, Do it when you feel like it.
The question is, can I treat my main tank with any type of medications the same way
Yes.
or does it effect the CO2 at all or anything I need to look out for?
No.
When the time comes to add some more livestock when is the best time to do so? Going from a bag with no CO2 to a fully gassed tank I would imagine could be stressful. Is there a rule of thumb for doing this?
Dont add new livestock to a tank with peak CO2 levels (30ppm or whatever you usually use).
CO2 and O2 are not mutually exclusive. As long as your tank is properly oxygenated and CO2 levels are not in deadly zone, you can add fish even when CO2 is present. I have never lost a fish by adding them during the photoperiod when CO2 was at peak. For shrimp it's best to acclimate them with the drip method.
 

Sacul

Member
Thread starter
Joined
10 Dec 2020
Messages
64
Location
Devon
Ok brilliant. Well it seems there is alot less to worry about than I initially thought!
 

Hufsa

Member
Joined
22 Aug 2019
Messages
1,344
Location
Norway
CO2 and O2 are not mutually exclusive. As long as your tank is properly oxygenated and CO2 levels are not in deadly zone, you can add fish even when CO2 is present. I have never lost a fish by adding them during the photoperiod when CO2 was at peak. For shrimp it's best to acclimate them with the drip method.
I haven't said they are mutually exclusive 🙂
Im gonna have to disagree with you on this point. Just because you haven't had a problem with it so far, doesn't mean its a good thing to do. Especially for those who keep more sensitive fish than the average aquascaper, adding fish who aren't used to elevated CO2 straight into a high tech tank is not a good idea.
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,362
Location
Thailand
Just because you haven't had a problem with it so far, doesn't mean its a good thing to do. Especially for those who keep more sensitive fish than the average aquascaper, adding fish who aren't used to elevated CO2 straight into a high tech tank is not a good idea.

My experience is irrelevant to be honest and was merely used to exemplify the prior statement which is a scientific fact.
During the photoperiod, that's the moment of the day were you will have the most O2 dissolved in the tank. Definitely not before (as that is the moment with the least O2), and not during the night. Obviously I am assuming one has plants and the tank is in good health. You can argue that there is plenty of CO2, but reality is that fish will appreciate far more being in the tank with some CO2 and plenty of O2 than contained in a bag, probably filled with water that is O2 depleted and already under stress.

I live in a country/region where fish are far more prevalent in people's home/office than in Europe or elsewhere. Asian people have a special relationship with fish for some reason. European/American would be shocked at certain practices here but reality is that one needs to respect their experience. What I described above is not some experiment I carried out, it is very common here and fish do fine.

So let's agree to disagree.
 
Last edited:

Yugang

Member
Joined
13 Mar 2021
Messages
336
Location
Hong Kong
So let's agree to disagree
Perhaps it is more productive to emphasise that fish need to be acclimatised, rather than straight from bag into tank. Irrespective CO2 or no CO2, because there are other factors as well that create unnecessary stress with a too sudden change.
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,362
Location
Thailand
Perhaps it is more productive to emphasise that fish need to be acclimatised, rather than straight from bag into tank. Irrespective CO2 or no CO2, because there are other factors as well that create unnecessary stress with a too sudden change.
Yes that's a given I think. I don't disagree with that. At least temperature wise. That's what I usually do. I put the bag of fish in the tank and let it float for an hour or 2 so that temperature balances out.
 

Yugang

Member
Joined
13 Mar 2021
Messages
336
Location
Hong Kong
I usually add a little tank water to the bag, and take a similar volume out that goes into the sink. Keep repeating. After half an hour my fish swim in 95% aquarium water, still in the bag, and virtually no water from the shop goes into my tank when I release them. The whole CO2 debate seems then less relevant, temperature and osmotic values are balanced as well.

Now I have to admit, I am not a really good fishkeeper, just try my best 🙂
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,362
Location
Thailand
I usually add a little tank water to the bag, and take a similar volume out that goes into the sink. Keep repeating. After half an hour my fish swim in 95% aquarium water, still in the bag, and virtually no water from the shop goes into my tank when I release them. The whole CO2 debate seems then less relevant, temperature and osmotic values are balanced as well.

Now I have to admit, I am not a really good fishkeeper, just try my best 🙂
Yes that's a good way of doing it indeed. I don't usually bother doing that with fish though, I don't think it's required but it doesn't hurt for sure. However with shrimps I am more careful and use the drip method for a good 2 hours before adding them to the tank. I never add the water from the shops in my tank. Ever.

Just to be clear things up I am not disagreeing with @Hufsa with her method of adding fish outside the photoperiod. I simply exposed something else to which she doesn't agree. But that's ok. We can't all agree on everything. It would be boring otherwise. 🙂 - Here's a 🤗 for Hufsa.
 

Sacul

Member
Thread starter
Joined
10 Dec 2020
Messages
64
Location
Devon
Thanks guys. My usual way to add fish would be to float the bag for an hour or so and adding water from the tank every 10 minutes then add the lot to the tank. I know all the guys at my fish shop and the water parameters are about the same as mine and new arrivals go into quarantine and medicated as needed so there water in my tank doesn't bother me too much, however other shops would be different. My only concern was the CO2 with fish going from a already stressful environment (bag) already breathing heavily to then being put in a tank saturated with CO2 making it possibly more difficult to breath. But I suppose while adding water to the bag every 10 minutes I'm slowly increasing CO2 and O2 anyway.
 

Wookii

Member
Joined
13 Nov 2019
Messages
3,169
Location
Nottingham
My usual way to add fish would be to float the bag for an hour or so and adding water from the tank every 10 minutes then add the lot to the tank.

That is the best way to do it, gradually exchanging the water over a couple of hours.

My only concern was the CO2 with fish going from a already stressful environment (bag) already breathing heavily to then being put in a tank saturated with CO2 making it possibly more difficult to breath.

You are right to be concerned. I don't think you should ever add fish directly to a CO2 injected tank with the CO2 at full tilt. It can take fish a week or more for their respiratory system to become acclimatised to the higher CO2 levels in my experience. Anyone adding fish to a CO2 injected tank, should be turning the gas off on the day of introduction, and then adding it back in gradually and incrementally over several days to get back to the original levels. Fish welfare should always come ahead of any plant needs.
 
Last edited:
Top