So you repeated what I said. How does that change the facts? CO2 is NOT sequestered unless it's permanently accounted for. We don't catch and release, we catch and keep, that is the whole point of the fact that algae could help us clean our atmosphere, not recycle it.
I have heard arguments touting the carbon neutral benefit of using algae as a fuel source (or any bio-fuel for that matter). But, I think it's wrong to tout algae as a way to significantly reduce the current levels of CO2 in the environment.