CO2 injection increased phyto culture density

fryman · Jun 24, 2021

Just for the heck of it I got a planted tank-style CO2 diffuser setup and ran a couple of otherwise identical phyto cultures side-by- side with one using injected CO2 and the other regular air pumps.

After 7 days the CO2-infused nanno culture reached a density of 10.1 million cells/ml, while the control reached only 4.1 million cells/ml.

The CO2 iso culture reached 7.2 mil cells/ml, control was 4.1 mil cells/ml.

I didn't include tetraselmis in the test because the week before I added circulation pumps to my cultures in anticipation of this test to see if the extra circation would affect anything. My tetraselmis actually crashed. Either tet doesn't appreciate the circulation, or maybe I just didn't clean the pump well enough (or possibly just bad luck?). Nanno grew a little better with the extra circulation (negligably), Iso didn't seem to care either way.

I think phyto is CO2 limited in typical air-pump cultures.

Jay Hemdal · Jun 25, 2021

What CO2 source do you use? Any evidence of self-shading in the dense culture? If CO2 was the photosynthesis limiter (and it often is in planted tanks) I wonder what the next limit would be, and when you would reach it?

jay

fryman · Jun 25, 2021

Jay Hemdal said:
What CO2 source do you use? Any evidence of self-shading in the dense culture? If CO2 was the photosynthesis limiter (and it often is in planted tanks) I wonder what the next limit would be, and when you would reach it?

jay

I used a 10# CO2 cylinder from craigslist. The guy I bought it from was using it for a home seltzer-water machine.

I'm not sure how to spot evidence of self shading but I added circulation pumps which I would expect should avoid it. I used cheapo koralia knock-offs from Amazon, brand is Sunsun but there's alot of circulation. I think maybe overkill actually.

I expect the next limiter is light. I noticed when using LEDs I have to be careful about PAR and I have killed cultures using too strong LEDs. But I've also grown phyto in direct sunlight, which measures like 2000+ PAR for me here in No Cal and yet doesn't fry the phyto. No idea why this is. I am thinking about trying natural sunlight.

Adam1985 · Nov 5, 2021

fryman said:
Just for the heck of it I got a planted tank-style CO2 diffuser setup and ran a couple of otherwise identical phyto cultures side-by- side with one using injected CO2 and the other regular air pumps.

After 7 days the CO2-infused nanno culture reached a density of 10.1 million cells/ml, while the control reached only 4.1 million cells/ml.

The CO2 iso culture reached 7.2 mil cells/ml, control was 4.1 mil cells/ml.

I didn't include tetraselmis in the test because the week before I added circulation pumps to my cultures in anticipation of this test to see if the extra circation would affect anything. My tetraselmis actually crashed. Either tet doesn't appreciate the circulation, or maybe I just didn't clean the pump well enough (or possibly just bad luck?). Nanno grew a little better with the extra circulation (negligably), Iso didn't seem to care either way.

I think phyto is CO2 limited in typical air-pump cultures.