jcbyrne

In his article in the Tropical Fish Hobbyist that just arrived, Amano says that to monitor CO2, measure the ph just before the light goes on in the morning, and again four to five hours later. If it is higher, the amount of CO2 is insufficient, if it is slightly lower, the amount is adequate. If it is much lower the amount of CO2 is excessive.

So, what do you think? What is "slightly lower", "higher" or "much lower"?

hoppycalif

It is permitted to disagree even with Amano! So, I do.

AndyT.

Well, think of it this way...

Overnight the plants release CO2 and consume O2... CO2 being acidic, this means that the pH should have dropped over the night.

During the day this reverses, with the plants consuming CO2 and producing O2. If you don't supplement CO2 the normal cycle would be for the morning to be the time with the lowest pH, just before lights come on. The pH should rise throught he day as the CO2 in the aquarium is utilized by the plants.

Back to what Amano says - I think he is indicating that an increase in pH would show that CO2 is being depleted in the aquarium faster than it is being replaced. So any increase would indicate that there is not enough CO2 supplementation (if you assume that the early morning CO2 and pH levels are ideal).

The pH scale is logarithmic and if I recall correctly (always a problem) each 0.1 change represents a 10x change in pH. A change from a pH of 8 to 7 is a 100x change.

So I would go for a decrease in pH of about 0.2 to 0.4 as being okay and anything larger indicating too much CO2 is being added. But that is just my take on it.

The much discussed drop checker is an easy way to use pH to monitor CO2 levels.

AndyT.

Hoppy, why do you disagree with Amano? The only thing I see as problematic is the assumption that the early morning CO2/pH level is a baseline...

hoppycalif

A change in pH of 1.0 equals a change in ppm of CO2 of 10X, not 100X.
I disagree with Amano, partly for the thrill of doing so, but mostly because I think we get the best results if we try for 30 ppm of CO2 in the water during the time the lights are on. Generally, that means the pH will be higher in the morning, after the CO2 has been lost due to our slight surface turbulence. Then, as we add CO2 while the lights are on the pH will drop until we hit the equilibrium point where we are adding as much as we are losing through the water surface.

I'm not quite ready to challenge Amano on the quality of my plant growing skills, nor on my aquascaping skills, nor on my algae control, nor............

DWIZUM

So hoppy, explain this in plain english - does your method add more or less CO2 than the big guy's?

essabee

Hoppycalif is right and so is Amano.

Andy T got the right point. It is the baseline.

Hoppycalif's baseline is the ph at 30ppm CO2. Amano's baseline is at perhaps that at the light on point.

It is certainly a fact that if the ph is higher 4/5 hours after the light on point, the CO2 supply is not equal to consumption.

Also those who have aerator on at light off point will have to find their own baseline.

I think it is totally subjective what you want to do with your CO2. Personally I have decided not to go for maximum growth, only sustained growth, that means fiddling with supply so that the ph goes slightly up or stays level at the end of the light on period.

AndyT.

I guess you can see why I was a liberal arts major...

Thanks for elucidating. Makes perfect sense now.

Salt

Edward and Kekon have posted lots of data showing CO2 levels don't have to be higher than 10 - 20 ppm to achieve fast growth and great looking tanks. Combine that with the countless pictures of tanks by Amano, and there's little questioning it. If you still want to believe you need to have 30 - 100 ppm of CO2 or that you need to turn it up until you see your fish suffering, then go on with your bad self.

Wheeler

This is a problem. The thrill? You think you get "better results", but you don't. I've never seen your tanks, but I KNOW that you don't get better, 100% reapeatable, results than Amano in any sense. Few do...

Amano does it with half the CO2, a small fraction of NO3 and PO4, and easily as much light as any EI tank.... again and again 1000 times over. Right now, Amano is untouchable. I think we'll get him figured out one day, but EI ain't it.