Well, it's started, my tank is on the slope down from "high-tech" to low-tech. The idea was to keep the current tank going and start up an El Natural in the second-hand Rio 125 that I've just bought. But... last night I noticed that the lights were off but the CO2 was still pumping away in to the tank - the solenoid had packed up with the valve open. This evening I removed all the CO2 kit and took out one of the bulbs. The tank is now low-light!