Hi all,
that the article is talking about low tech tanks?
It is, I'm not a CO2 user. I know that plants are the most important factor in maintaining water quality, and I want plec keepers etc to keep planted tanks, because it gives them more chance of success.
"we should definitely not add CO2 to tanks containing plecs"
It is largely to do with fish physiology and the
<"Bohr-root effect">. Rheophilic fish don't have any physiological adaptations to high CO2 levels, and can be asphyxiated even when dissolved oxygen levels are high.
The problem is that the haemoglobin in the blood transports both oxygen and CO2. If you have high CO2 levels in the tank water the gradient between blood CO2 and the water is reduced and CO2 diffuses out of the gill surface more slowly. If a CO2 molecule is bound to the haemoglobin molecule, it can't accept an oxygen molecule.
High tech tanks have a high rate of photosynthesis and O2 production. This could perhaps make lots of surface agitation counterproductive to maintaining high O2 levels?
No, it is like
@Zeus says, but it will out-gas
added CO2 more quickly. Have a look at the "Bouncy Castle" analogy (in <"
pH drop & high.....">) for an explanation.
Once the water is fully saturated with oxygen it can't hold any more and it out-gases (this is "pearling"). It is different with CO2, you can dissolve a huge amount of CO2 in water (think of a carbonated drink).
Because dissolved gases are difficult to measure we often use pH as a proxy for changes in the ratio of CO2 and dissolved O2. Oxygen is a base (the hydroxyl ion is really O-H, rather than OH-) and CO2 an acid (or more correctly a small proportion of dissolved CO2 becomes
<"carbonic acid (H2CO3)">), and pH is the ratio of proton acceptors and donors.
Have a look at
BigTom's posts in <"
Maxing CO2 in low tech....">, the whole thread is worth a read.
cheers Darrel