Lethal Level of CO2

[wolfiewill]

So, I now know what the threshold for CO2 concentration is for Platys, Endlers and Cherry Barbs. Does anyone know of a pH v KH chart to calculate a pH of 4.4 and a KH of 14? My chart for high KH only goes to a pH of 6.0, and that, people, is a whopping 420 ppm of CO2. I think I saved some of each of the above, but all the Cherry shrimp and the SAE are dead. The plants look good though. Can anyone say 'pH CONTROLLER!!!!'.

[zolta]

Ouch.

Sorry to hear. Don't have a chart though.

[daworldisblack]

ooooh... wow thats crazy! Sorry to hear! Thats an insane amount of co2!

[fischkopp]

SAE are know to be sensitive to CO2 and one of the best indicators for CO2 levels. Refer to "Chinese Drop Checker" ...

[Jeff1192]

I used to always use a CO2 drop checker. They're great and make for an easy way to monitor your CO2 levels.

[wolfiewill]

This isn't one of my tanks, it's a tank that I look after for a friend. He didn't want a pH controller, and it's only a 20 gallon tank. He's away and I don't think a drop checker would have done any good under the circumstances.

[exv152]

Hey wolfiewill, your best bet is to start slowly, adjusting co2 and observing based how the fish react. When the tank is being buffered (like your friend's obviously is with such a high KH and low pH) you don't want to aim for a 1 point drop in pH. Add co2 to the point where the fish are slightly uncomfortable, and then dial it back. You may only need to drop the pH by 0.5 or 0.4. It all depends on how the fish react. The pH/KH chart doesn't take into consideration buffers, and drop checkers can takes hours to react.

[wolfiewill]

That's what we did.... a year ago. Although we certainly didn't add enough to cause any distress to the fish. I choose approximately a 0.5 to 1.0 pH unit drop and worked from there. We found about one bubble per second dropped the pH about 0.8 unit - to about 7.5. The plants do really well and the fish were all in good shape. At the time, I recommended a pH controller to him rather than the bubble count method, I thought it important 'cause he travels a lot and wouldn't be continuously monitoring the tank pressure to change it out when it dropped below 500 psi. And this situation is exactly what I was afraid of. He's away, and I was only able to check it once or twice a week (when I was in town), and this isn't something that would have been caught that way. He didn't want to pay for the pH monitor. He returns home today, so we'll see if he has a change of heart.

[lucius]

I find my fish act funny when my plants reach the top and cut off the flow across the top.

[exv152]

I wouldn't recommend distressing the fish like adding so much co2 that they'll be gasping at the surface, but certainly, if you know how your fish react normally, you'll notice their behaviour begins to change with higher ppm's of co2. Another work around for your scenario would have been to use a dual stage regulator that will maintain the working pressure consistent until the co2 cylinder is almost bone dry.   It sounds like an end of tank dump caused by a single stage regulator.

[wolfiewill]

I wouldn't recommend distressing the fish like adding so much co2 that they'll be gasping at the surface,

Fish, smish..... who cares about the fish!

Another work around for your scenario would have been to use a dual stage regulator that will maintain the working pressure consistent until the co2 cylinder is almost bone dry.

But, I think that the extra cost for a dual stage regulator would probably cover most of the cost of a pH monitor, and the pH monitor has the extra advantage of allowing better control of the pH target as well.

It sounds like an end of tank dump caused by a single stage regulator.

Yes, I agree. I think that's exactly what it was. And a pH monitor would solve the problem.

[exv152]

Agreed. But don't be too lured by the cheap single stage regulators. There's a lot of value in getting a dual stage regulator, even used. Take a dual stage, and add a pH controller, and you've got the best of both worlds. The pH controller will save you a tonne of co2, prevent EOTD, and will maintain a target pH/co2. While the dual stage reg will give you consistent co2 delivery with no drifting, and it'll prevent an EOTD should your controller fail. Also, the cost of one used dual stage is cheaper than having to buy two or three milwaukees over time.