Which one? That there is bacteria and viruses in water or that an RO unit filters these out?

If you are thinking of going the booster route, Aquasafe's unit is $85 USD, delivered.

http://www.aquasafecanada.com/accesories.htm

Thanks, I think I may well go that route.:biggrin:

As for the bacteria and viruses. I should hope that my tapwater has been treated enough that it doesn't contain any of those. I'm mostly more interested in how available nutrients are for algae fuel.

That is a good price, but a couple things to consider:

It doesn't have auto controls (so you have to have it on a timer or only plug it in when you make water)
It only goes up to 80psi (mine goes to 90-110 psi and I get better rejection from my RO that way)