CO2 Chart

[efish]

so is this really needed for DIY CO2? Good thing I wasted the money on a kH and gH tester.

[CmLaracy]

according to this I have over 100 ppm CO2 in my tank....

I have a KH of 3.5, and a pH that drops down, BELOW 6. I don't have any fish in the tank, and I'm using an ADA diffuser at 3bps in a 42 gallon.... My GH is also at .5

Is my CO2 really at over 100ppms?

[Homer_Simpson]

Originally Posted by CmLaracy

according to this I have over 100 ppm CO2 in my tank....

I have a KH of 3.5, and a pH that drops down, BELOW 6. I don't have any fish in the tank, and I'm using an ADA diffuser at 3bps in a 42 gallon.... My GH is also at .5

Is my CO2 really at over 100ppms?

Hmmm.....interesting, I guess different KH and PH readings can cause wide fluctuations to the point where the readings may or may not be accurate. I have a 10 gallon where water parameters tested monthly over 6 months would suggest that water parameters would be in the range considered ideal for plant growth, but the tank was plagued by fish deaths and very poor plant growth. As per drop checker the c02 level was 30 ppm, but as per on-line chart it was only 11.7 ppm. In that case, I was more inclined to believe that the on-line chart was more accurate, since black brush algae was one of the first types of algae to materialize and this usually materializes when
c02 levels are suboptimal.

[poptarts356]

how long will a 20lb co2 tank last for aprox. to get good levels in a 200gal tank? any good guesses

[wkndracer]

[quote=poptarts356;733474]how long will a 20lb co2 tank last for aprox. to get good levels in a 200gal tank? any good guesses[/quote

Running off the same cylinder (20lb) feeding two 75g tanks for over 6 months without any pressure drop. Drop checker color green/yellow green through Rex style reactors using AM controllers.

[Cardinals]

Originally Posted by Hoppy

If you read carefully, Chuck Gadd notes in his discussion that the equation is not valid for water that isn't "perfect".

Is it possible to have an planted tank pH 7 @ 6dKH without supplemental CO2 or non carbonate buffers (e.g. phosphates)? According to the chart CO2 would be ~18ppm, well above normal equilibrium values of 0-5ppm

[qwiksilvertrav]

I found these charts to be pretty inaccurate. I used it just before getting a drop checker and had a PH of 6.6 and a KH of 6.5 telling me I had over 70 ppm of Co2.

I then put in the drop checker and it read a slightly dark green which is about 20ppm of Co2. I turned up the Co2 a little bit and got it at 30 - 40 (lighter green) and boom the plants started pearling like crazy. Other tests have indicated this chart not reading out how my drop checker is reading. I trust my drop checker over this personally.

[Cardinals]

Originally Posted by qwiksilvertrav

I found these charts to be pretty inaccurate. I used it just before getting a drop checker and had a PH of 6.6 and a KH of 6.5 telling me I had over 70 ppm of Co2.
I trust my drop checker over this personally.

If I've looked at the chart right, pH 6.6 dKH 6.5 equals 49ppm CO2?
Doesn't a "drop checker" actually measure the pH (using bromothymol blue), not CO2. CO2 is then deduced from the chart according to your KH?
If your "drop checker" is green, using bromothymol blue, pH is ~6.6. Therefore, if your dKH is still 6.5 your CO2 is ~49ppm. However, if you have reduced your dKH to 4, then CO2 ~30ppm. (using the charts)
If you are interested, I am using excellent LaMotte CO2 titrator which could be used to verify your tanks parameters.

[Hoppy]

The whole point of using a drop checker is to make the CO2 chart work. It doesn't work when used with typical aquarium water, because there are too many things in the water that affect the pH, other than just carbonates and CO2. With a drop checker you are measuring the pH of a tiny bit of water that contains nothing affecting pH except carbonates (bicarbonates) and the CO2 that equalizes between the drop checker water and the tank water. The La Motte CO2 test is also a pH/KH test, so is also inaccurate. But, you can buy a CO2 probe and meter that will very accurately measure the CO2 concentration in the tank water, and do it very fast. All you need is a couple thousand dollars to spare.

[mistergreen]

there are a lot of variables in a tank that affect the ph & kh, so the CO2 chart is inaccurate for the most part.

In a drop checker however, the KH is constant.. the PH changes depending on the amount of CO2 available.

[Left C]

Originally Posted by Cardinals

Is it possible to have an planted tank pH 7 @ 6dKH without supplemental CO2 or non carbonate buffers (e.g. phosphates)? According to the chart CO2 would be ~18ppm, well above normal equilibrium values of 0-5ppm.

Originally Posted by Cardinals

If I've looked at the chart right, pH 6.6 dKH 6.5 equals 49ppm CO2?
Doesn't a "drop checker" actually measure the pH (using bromothymol blue), not CO2. CO2 is then deduced from the chart according to your KH?
If your "drop checker" is green, using bromothymol blue, pH is ~6.6. Therefore, if your dKH is still 6.5 your CO2 is ~49ppm. However, if you have reduced your dKH to 4, then CO2 ~30ppm. (using the charts)
If you are interested, I am using excellent LaMotte CO2 titrator which could be used to verify your tanks parameters.

You most likely have other buffers present than carbonate/bicarbonate buffers in your aquarium since it is planted... Namely some phosphates which are much stronger buffers as you know.

"NOTE: If you aren't adding CO2 to your water, and the CO2 level based on the pH and KH indicates more than 5ppm, then it is very likely that some other buffer (such as phosphate) is present in your water. In an inhabited aquarium, the amount of CO2 produced by the fish will not have an effect on CO2 levels in the water. Any excess CO2 created by fish will dissipate into the air, leaving a fairly constant CO2 level of about 3-4ppm. If you test your pH and KH, and without adding any CO2, the chart says you've got 20ppm CO2, don't believe it. "

The above quote is from: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

Most people don't rely on that chart anymore because of several variables including phosphate buffers, other acids and bases involved and inaccuracy of hobby grade test kits.

[qwiksilvertrav]

Sorry I misposted my numbers, I actually had a PH of 6.4 and a KH of 6.5, not a ph of 6.6..my bad. I put in my drop checker the next day and after some adjustment and increasing the Co2 it was at 30 - 40 ppm and the plants began to pearl like crazy. It most definitely was NOT at 70ppm like the chart was telling me.

[plantbrain]

Originally Posted by qwiksilvertrav

Sorry I misposted my numbers, I actually had a PH of 6.4 and a KH of 6.5, not a ph of 6.6..my bad. I put in my drop checker the next day and after some adjustment and increasing the Co2 it was at 30 - 40 ppm and the plants began to pearl like crazy. It most definitely was NOT at 70ppm like the chart was telling me.

And since many rely solely on the chart as their metric for CO2, how might this over estimation, this belief that their test method tells them that there is much less CO2 in there than is really the case....might affect plant health, growth and algae?

The chart might work for some folks, not for others. This is a known fact and observation.

So there has to be another issue occurring besides those 2 parameters, pH/KH.

The drop checker gets around that, but............how accurate is the color changing in the DC? Can you tell between say 18ppm and 24ppm of CO2 with a DC? After adding CO2, how long does it take for the checker to change color?

How often should they(DC) be changed? What about placement of the DC?
It's a rough guide and slow to change device.

You give up one good trade off, and gain another, without really knowing if the CO2 is accurate or not.

Algae, plants, eyeballs , Riccia stones, fish, shrimp etc...........all these are perhaps better test kits for CO2. Or a mixture of all 3 methods, livestock/bioindicators, CO2 charts, and DC.

Do not rely too heavily on any one thing other than livestock.
"They" do not lie.

But folks need experience and to be careful, CO2 kills 99.99% of the fish with dosing errors, so it demands respect!

Regards,
Tom Barr

[!shadow!]

+1 on the above post. People usually have to find out the hard way in which l did when l was younger when my fish were gasping at the waters surface until l had to quickly add in some air stones and correct that problem. luckily none of the fish died. Anyways l couldn't agree more on that>> "Do not rely too heavily on any one thing other than livestock.
"They" do not lie." Basically don't be ignorant and follow just 1 sort of rule be open minded and experiment. Experience is often the best teacher!

[StaleyDaBear]

What really are we talking about? We get around dosing checks with the EI method. Then, if we experiment using fish gasping, algae and pearling as a point of reference in upping or lowering our co2, is this just not another form of EI dosing? The chart and drop checker get no closer than we ourselves can predict with a close eye on our fish and tanks, and small changes in bps. Probably a better estimate considering we dont have restrictive limitations (numbers) and nor do our planted tanks.