All other waterfall algae scrubber designs (which we created in 2008; see Ats2008.org) require you to disconnect and disassemble the unit to get to the growth on the bottom tray. This was a problem. The RAIN2 and RAIN4, which we created to solve this issue, allow you to lift off the LED dome lid with one hand so you can observe any growth on the tray, and then you can lift the tray off of the water pipe also with one hand (as shown) to take it to your sink. And you never have to turn off the water flow when doing this.

Click image for larger version

Name:	rain tray growth 2.jpg
Views:	15
Size:	71.1 KB
ID:	8336