Can I turn carbon reactor back on?

[asylumdown]

because after that long without water running through it all the oxygen in the reactor will have been consumed and by now you've got a host of anaerobic bacteria in there that may or may not be producing all sorts of poisonous gasses and by-products. In a large aquarium it will all probably get gassed off and the bacteria will be killed shortly after you turn it back on, but if it's a smaller system you could end up dumping a bunch hydrogen sulphide in to your water, along with anything else that's built up as a result.

At worse, something bad will happen, at best, the carbon that's in there has been absorbing a weeks worth of gasses and metabolic wastes from anaerobic bacteria and it won't be as effective as it should be for how long it's been in your system. I'd just replace the carbon and start again.

I dunno, I'd rather have fresh carbon in there doing what I bought it to do than something that may not be effective anymore.