The Technical Research Centre of Finland LTD (VTT) and the University of Turku, Finland are developing a simple, do-it-yourself test for detecting the presence of toxic blue-green algae in water:
http://www.utu.fi/en/news/articles/Pages/Novel-Testing-Device-for-Blue-green-Algae.aspx
At the moment it looks like this:
Picture: Pirjo Hakkarainen VTT
Now this should be taken to th next level – make it commercial. Interested? Contact VTT.
22-6-2016:
They still need somebody to commercialise it. Take a look: