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More CO2 questions

Sacul

Member
Joined
10 Dec 2020
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89
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
 
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.
 
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.
 
Ok brilliant. Well it seems there is alot less to worry about than I initially thought!
 
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.
 
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.
 
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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.
 
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.
 
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