upper CO2 limits

yme

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yesterday I was playing around with the CO2 outlets etc to get a better current/flow. To do so I removed the pH meter from the tank and put in in glass of tapwater (pH 8.0). After a while, I placed the pH meter back in the water and the pH was 6.14! normally the pH is 6.30 and the CO2 level is 40 mg/l. I didn't measure the CO2 level at that pH, but it must be around much higher than 40 mg/l (50?). but yet, the fish didn't go to the surfaceor showed any discomfort during the time. So I am now really wondering what the upper limit of CO2 is for fish and also my amano shrimps. For sure I do not want to kill them...
Did anyone do some experiments?

greets,

yme
 

Gilles

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Most of my shrimp died over the vivarium event. I think i overdosed flourish excel although my PO4 was on the high side too.
 

Tom Barr

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It really depends where you take the CO2 reading.
And the flow rate past the probe.

I had 100-60ppm in the spot near the high flow from a mazzei, in another lower flow region, about 30ppm, inside the plant beds, about 15ppm.

3000 gph in a open layout for a 180 aquarium.

Time to stable CO2 reading was about 5-10min.
45 ppm had no adverse effects on Discus at a spot in the large behemoth tank, but as you can see, there's going to be variation in the readings depending on where and the flow.


Regards,
Tom Barr
 

yme

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hmmm...

let's see. you do measure way more variation than I do. in my case I see only about 5 mg/l difference. One difference I only realised now, is that I always turn off the CO2 when I measure. Just based on the assumption that the microbubbles hang on/at the membrane and thus errors the measurement. Based on your statement about high levels CO2 at the mazzei, you do not turn of the CO2.
Am I wrong in turning the Co2 off?.

I still find the difference in response time weird. my co2 levels are stable after 30 minutes....

anyway..... 45 mg/l might be oke.....

thanks!

yme
 

abcemorse

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On a related note of curiosity, if no fish are present can there be too much CO2 for plants?
 

SuperColey1

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I think the variable here between yours and toms may be because he is measuring CO2 gas.

You are measuring Ph which means you are using the equivalent of the Ph/KH chart which is virtually dismissed as highly inaccurate on most forums!!!

However your change seems strangely high to me from 8 to 6.3 let alone 6.14.

I wonder how it can change so far? Do you know your tank water KH?

AC
 

yme

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sorry to say...

but I have the same oxyguard CO2 analyzer as tom has :D :D

and I have to say that I don't use tapwater in my tank --> 100% RO water with sera mineral salt. KH 2.2. pH 6.3 gives 33 mg/l. But I measure 40 mg/l. and the change goes fast with 2 rhinox diffusors.

and as far as too much CO2, i don't know for sure but I gues that you have to go really really high before you see toxic effects.

greets,
 

Henry Hatch

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yme;35358 said:
sorry to say...

but I have the same oxyguard CO2 analyzer as tom has :D :D

and I have to say that I don't use tapwater in my tank --> 100% RO water with sera mineral salt. KH 2.2. pH 6.3 gives 33 mg/l. But I measure 40 mg/l. and the change goes fast with 2 rhinox diffusors.

and as far as too much CO2, i don't know for sure but I gues that you have to go really really high before you see toxic effects.

greets,

I suspect you may be correct. I don't have the equipment to measure co2 like you and Tom. However, I can observe the plants and fish. My drop checker is always yellow green to yellow without a hint of fish stress. I use the drop checker as a guide but my fish and plants are the ultimate authority.

Also I read the results of Tom's co2 measurements and that suggested to me the importance of good circulation. I don't know if that is the correct conclusion, but it was mine.

Henry
 

SuperColey1

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Hold my hands up then ;) I have no idea. lol

I suspect the low KH causes the hgh Ph fluctuation bu tI woldn't worry about that.

I don't particularly take much notice of my DC either. I let it go whatever colour it wants which can depend sometimes on whether I have topped up the water level and therefore gone from ripples to waves. lol

I don't notice any stress with the fish though :)

AC
 

vella.matt1990

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New to this forum...

Can someone please tell me how to regulate my co2 out-take...
I have a 130 liters aquarium .. with a 1200 lph haqos cannister filter and an inline reactor.. [ situated at the pump's outlet and before an 18 watt uv sterilizer!] I am still not understanding the ppm measure and the bubble per second measure.. I have also bought a co2 test kit.. to be on the safe side.. but still need some help!!! :p thank you all in advance :D
 

shoggoth43

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Where/how are you getting your CO2? This might help a bit. You might also want to open another thread for this as more people might notice your question and chime in.

The PPM measure is done either by a very expensive meter like Tom has, or using a drop checker with a known KH solution and pH color change liquid inside. When the color changes to green or yellow green you're probably good to go if you use a 4 KH liquid.

The bps is somewhat arbitrary and depends on your bubble counter and the liquid you use inside it. The bps won't get you too much as using a reactor vs. a diffusor or a needle wheel will require different amounts of CO2 to get the same ppm. It WILL give you an idea of how much relative CO2 you are using on your tank for any of the given methods that you try, but your count and your results probably won't closely track what another person uses unless you're using the same methods they use.

Another point to consider is the CO2 "misting" method where you don't try to dissolve all the CO2 but instead want to get really fine bubbles which stick to the plants and get used up directly. This method is arguably more efficient for the plants but will show much lower ppm readings in the tank.

Hope that helps a bit. Read around the forums a bit and just look at some of the different methods and don't be afraid to try a few different methods.
-
S
 

timmo11

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SuperColey1;35357 said:
However your change seems strangely high to me from 8 to 6.3 let alone 6.14.

I wonder how it can change so far? Do you know your tank water KH?

AC

Hi Coley

His tank pH never changed from 8 to 6.3. He simply put the probe in a glass of tap water (pH 8) to fool the CO2 injector to switch stay on.

Tim