Aquarium bubbly things

Yes and yes. Six stones in the J&S coolant settling tank, one for each compartment. Run from a timer :-)

Although switching from Hysol Excel to Vcut-SS has lessened the need for it, since it doesn't seem to get infected as quickly.

Mark Rand RTFM

I've got one in the Harrison M300 coolant tank, as to whether it works, its only been running for an hour a day for the last 4 years or more and the coolant hasn't gone bad yet. Time will tell. I expect I should think about the life of the corrosion inhibitors as they may have expired. I don't actually use the coolant that often though and clean down the wet surfaces after its use.

As usual with these unintended uses of items I went into a pet store and told the assistant what I was doing, expecting a strange response, but she just mentioned that for what I wanted their cheapy £10 starter kit with pump, stone, and pipe would in all likelyhood be fine, it has been. A timer for £6 or £7 from the local DIY store and it was put to work.

coolant

I'm intrigued why you are both using timers, as the pumps I've looked at are extremely low consumption - 5 watts or so and probably less than the timer!

AWEM

If you have it running all the time, the coolant will disappear quite rapidly. My shed is dry enough that I get significant evaporation even without the bubbler. My pump takes 4.5W and the clock takes .25W, but it's the evaporation that I do it for.

Regards Mark Rand RTFM

They work because the sulphate reducing bacteria (SRB) living in the bottom are anaerobic, i.e. they don't like oxygen. Stir them up and add oxygen and they die.