May Meeting

Ltrepeter2000 · Post by **Ltrepeter2000** » Tue Jun 02, 2009 1:54 pm

The downward spiral of politics. Isnt it Grand!!

DelawareJim · Post by **DelawareJim** » Tue Jun 02, 2009 2:33 pm

OMG!!! And I joined GWAPA to get away from that!!! At least for work I can sleep on the way to work and back! I might have to rethink this 3-hour drive one way.

Cheers.
Jim

DonkeyFish · Post by **DonkeyFish** » Mon Jun 08, 2009 3:55 pm

Everyone, your slacker Secretary (LOL) has finally posted the meeting notes from our last meeting. Hope they help someone somewhere!

Ltrepeter2000 · Post by **Ltrepeter2000** » Mon Jun 08, 2009 4:08 pm

Jen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for PrezJen for Prez

Woo hoo.

ingg · Post by **ingg** » Mon Jun 08, 2009 4:41 pm

A question/statement.

The write up makes it seem as if CO2 is somehow eating ("depleting" is what is said) Oxygen. This isn't the case I don't think. O2 and CO2 levels are independant of each other.

There are two main reasons for fish gasping in a CO2 enriched tank.

One is the acidity of CO2 itself - in essence, CO2 breaks down into an acid - which in high enough concentration burns gills and removes the livestock's ability to process oxygen - however, the amount of oxygen in the water column does not change, or am I mistaken?

The other is that in a heavily stocked tank, night time can potentially, but rarely, be a challenge vs. a non-planted tank.

Explanation: In a non planted tank, there is almost always ample surface agitation via HOB filters and airstones to cause the water to intake gas (Oxygen) from the atmosphere.

In a planted tank, we often strive for no surface agitation (to retain our CO2 levels, a process known as "offgassing" via surface agitation). In addition, the "plant action" of producing O2 stops when the lights go off, and plants instead respire only CO2 during the night.

This means that there is no oxygen "intake" or source during the night time like during the daytime cycle as well as no surface offgassing, and you can potentially wake to gasping fish in a very heavily (over) stocked tank. Same thing though - CO2 levels do not in and of themselves affect O2 levels.

jcali10 · Post by **jcali10** » Mon Jun 08, 2009 5:17 pm

I've read that fish produce modest amounts of CO2. I've never read anything about the quantity of CO2 respiring plants give off. I read that decomposing detrious in mature tanks can be an effective CO2 source to support plant life in an aquarium. And the symptoms from CO2 poisoning, ammonia poisoning and oxygen deficiency are all similar.

Post by **krisw** » Mon Jun 08, 2009 5:29 pm

Dave, honestly, I'm not sure what exactly is going on when the CO2 levels get too high, and fish start failing to "breath." CO2 is more soluble in water than O2, so is if the CO2 concentrations get too high, the oxygen can more longer absorb into the water? Honestly, I'm not sure. I suppose we could reword the article to just have folks "be careful" as the end result is still suffering fish.

ingg · Post by **ingg** » Mon Jun 08, 2009 6:20 pm

jcali10 wrote:I've read that fish produce modest amounts of CO2. I've never read anything about the quantity of CO2 respiring plants give off. I read that decomposing detrious in mature tanks can be an effective CO2 source to support plant life in an aquarium. And the symptoms from CO2 poisoning, ammonia poisoning and oxygen deficiency are all similar.

Fish do - but ambient (meaning without additional "artificial" sources can rarely reach over 4 ppm.

(BTW, so do plants, 24-7, part of the respiration/growth cycle of plants produces CO2 - they just consume more CO2 than they make during photosynthesis - and produce 10-30 times more O2 than they use, as well.

).

Decomposing, sorta, but not really - nitrifying bacteraia also consume CO2, so those is sort of a closed loop and only self sustaining system.

Symptoms are similar - in all cases, the fish feel choked, and hit the surface for the relatively rich O2 levels to be found where gas exhcange normally happens.

krisw wrote:Dave, honestly, I'm not sure what exactly is going on when the CO2 levels get too high, and fish start failing to "breath." CO2 is more soluble in water than O2, so is if the CO2 concentrations get too high, the oxygen can more longer absorb into the water? Honestly, I'm not sure. I suppose we could reword the article to just have folks "be careful" as the end result is still suffering fish.

Can't say I'm 100%, but I am 95% - this is one of those things I had to read up and study on when being a moderator on a general fishkeeping board... sort of an "Oh CRAP I don't really know the answer!" sort of dilemma when it came up.

And when it is all beginners for planted tanks, it comes up often.

I'd just ask we re-write it to note dangerous levels, but there is no depletion of Oxygen - the way it is worded only propogates the (incorrect) myth that CO2 displaces O2. (And being an ex-mod of general fishkeeping forum is why I'm nitpicky on it, I had to dispel that myth more times than I like to/want to remember).

Interesting trivia note - CO2 (more accurately, carbonic acid that it becomes in solution) is what makes Coca Cola the great cleaning solution in home cleaning tips - it puts the acidity of the soda a little higher than Vinegar.

SCMurphy · Post by **SCMurphy** » Tue Jun 09, 2009 8:32 am

CO2 does not displace O2. CO2 dissolves more like a salt, meaning it dissociates into ions in a solvent. O2 dissolves because of the partial pressure law and that amount varies with temperature, the same for nitrogen. In a volume of water with no biological activity occurring, O2 and N2 will be in solution in the proportion they exist in the atmosphere, while CO2 will be at a ratio higher than the atmosphere, independent of temperature (normal life sustaining temperatures). Fish gasping at the surface means you have a low O2 level, something that can be cured with an airstone and pump. I run my CO2 24/7, I don't get any symptoms of O2 deficiency, in any tank, the ones with or without surface agitation.

CO2 will be buffered in the carbonate/bicarbonate process so unless you have no buffering capacity in your water, (it does happen) you won't have a problem with CO2 poisoning.

Post by **krisw** » Tue Jun 09, 2009 8:51 am

Sean, I don't follow 100%... If CO2 doesn't displace O2, and fish gasping is due to low O2, not CO2 poisoning, why isn't there enough O2 when the CO2 levels get too high?

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