Brian, really nice set up, has me thinking about your set up now, I was going to go really big in a sense but may not have to now. As Jesse asked above can you provide Phos update? Remember, make sure the water tube is really clean - no smudges/fingerprints/debris. This Hanna checker passes a light through the water column in the tube to get its data. Keep us posted. Thanks for sharing your creative reactor idea!