Thanks for the links - really useful.
I came across some more videos on YouTube and this one (source included) looks interesting...
•5 separate LED Channels for White, Blues, Royal Blues, UV, and Red
•6th Channel for a Sump/Refugium LED Light
•7th Channel devoted to a Real Time Lunar Cycle
•Advanced LED testing features
•Water & Heatsink Temperature Sensors
•Control of a Heater and Chiller
•Audible & Visual Alarm Notices for Defined Temperature Variances
•LED Heatsink Temperature Sensor
•Dynamic Speed Control for Heatsink Fans (Display & Sump Lights)
•Wave Maker / Powerhead control
•Automatic Fish Feeder
•24HR & 12HR Time Formats AND Month DD, YYYY & DD/MM/YYYY Date Formats
•Settings & Preferences stored in EEPROM (Arduino Memory)
Although mine is fresh water - most of this could be really good for me to play around with.