I know it's an old thread, but I came to the same conclusion by observing where the BBA grows in my tank. It's like someone has drawn a line through the tank and told the BBA to settle there, and when I thought about it a bit more, it's where my koralia powerhead blows. I only thought of it because I have a very large anubias broadleaf that had never had any algae until I stuck the powerhead near it. BBA appeared soon appeared on the nearby leafs and the same effect can be seen all along in the direction of the flow of the powerhead. On a side note this powerhead is a bit overkill for my tank which could be one of the reasons, but it hasn't blown away any fish or fry for example, just a bit harsh on the fry of course. I used to have it on the other side of the tank, blowing at another anubias by accident, and that's where I first got a BBA outbreak but I never related the two together at the time.
I think I read in Diana Walstad's book "Ecology of the planted aquarium" about plants suffering in too much flow, not being able to utilize the nutritients/CO2 when there's too much flow passing over their leaves as it passes too fast, or something of the sort, I can't remember. Or is it just mechanical damage, leaking nutritients from the leaves and high flow algae species havng a feast in those conditions?
Otherwise you'd thik the higher the flow, the more nutritients and CO2 for the plants in that area but certain algae species seem to love that more than the plants.
Anyway, it does seem that BBA has a lot to do with the flow whether directly or indirectly CO2 related or not, but it does establish itself better in the most turbulent areas of the tank from what I've seen. Maybe the high flow just washes off the CO2 away too fast for the plants but BBA has adapted to thrive in this conditions?
