Here is a customer's RAIN4 scrubber® in a sump. Note the waterline is touching the bottom of the tray; this eliminates any distance that water has to fall down a drain, and thus makes it dead silent. They tray can even go under water if needed, for room. The waterproof submersible GEM5® lights make this possible (see LEDsafety.org)
Not shown here is the easy one-handed removal of the dome lid off of the tray, or the entire dome/tray off of the pole mount. This is a patented function of the Rain models.