Well, I used the bleach, but I also rinsed after, then soaked in warm water for two hours, then rinsed again... Hopefully that will be fine. Either 1. now that the driftwood is completely clean it looks much lighter, or 2. the bleach lightenend it, but it still looks okay

New purchases for tomorrow:

2 x Thermometer

New Thermostat

We'll see how that all works out... No more ratioing out multiple thermometers and checking how much it varies every two hours... Although at least if something goes wrong in the future I know how quickly the tank looses heat in the current temperature settings!!!