Because that is simply not the case. How does freshwater algae spread into dry stream beds, puddles that recently form etc? Are you willing to practice sterile technique on all aspects of keeping plants etc?
I'm not.
Fish, food, air born spores of algae, plants, nets, water from the LFS etc........ many sources.
So if that is the cause, where is my algae then?
I have plenty of BBA exposure and yet it never grows.
Can you explain this observation?
I can take healthy actively growing BBA, and add it to this tank and it does not live.
So this logic fails for inoculation from other sources. It does not address why you have it or the cause. The problem is you have little idea why the BBA is there and are simply reading 101 claims and most newbies have this same issue as did myself way back when(it was much worse).
They did not look at what germinates algae in an aquatic planted tank.
Yes, the spores have to get there, but that's pretty easy, prevention of spores has yet to save anyone I am aware of. Perhaps with a few green species, and even that is a maybe.
The other issue for most newbies with algae issues is a lack of a reference control where the plants are growing well to test their ideas. Few also want to test and see etc, they just want the problem to go away. If they could produce such a tank, then they would not need to test in the first place.
So they have troubles and have to take some things on faith.
Till you learn more and get a handle on it, that will not change.
I've been down the same path with algae in every form.
So I try and help and tell folks where to put their efforts to reach that goal.
Many do their own thing and learn the hard way. I did. Up to you, but it's a much longer more painful road.
SAE's are the best BBA control fish/critter.
Regards,
Tom Barr