Thanks for the advice. I may come back to this in the future.

Yeah I need a compressor really.

+markanne54 Geez that never crossed my mind. I'd imagine a professional solutions would have something antibacterial chemicals present but seeing as I was going to bi-carb maybe ill throw some Dettol in there as well.. or I'll use a drip feed instead which could be cleaned more easily?

+Educating Savvas Professional misting systems used for agriculture/botanic use tend to be designed to have ultra-violet sterilisers as well as rigid regimes of regular testing and disinfecting, and lastly get designed so that they minimise stagnant water as much as possible, so they have circulating systems and auto-drains on the final legs to the mist/spray heads, for example. Such systems can't have aggressive chemicals injected into the water during use as it would affect the plants. I have also seen systems that inject silver into the water which kills bugs but not plants, but they're very expensive to run and maintain. Liquid cooling systems on machines don't present as much of a threat. The real problem comes from aerosolising water and spraying it in the air. It's a perfect route for bugs to get into our lungs, where they do the real damage. Legionella pneumophila is but one of the nasties that will breed in a water system, normally causing no harm - until it's aerosolised in some way, such as in a badly designed cooling tower - or you deliberately aerosolise it, of course.

+markanne54 This sounds like a lot of effort, especially considering I was only planning on milling aluminium occasionally. The small aquarium compressor didn't atomise the liquid, so that would be the safest option in retrospect. I could also dismantle the block after use and let it dry properly. But it all seems like a lot of work when a syringe with alcohol would do. That last thing I want to is increase the chances of getting pneumonia. Thanks for the advice.

+Educating Savvas I think you're right. A quick injection of some sterilising fluid before and after use would be appropriate. Detol, Jeyes Fluid or even dilute bleach would probably suffice.

+John Fithian-Franks They can be a similar price to the aquarium air pump on ebay - but I want to wait a little before forking out more dosh on this machine. Maybe I'll find one second hand or I could try use a drip feed in the meantime as was suggested in an earlier post?

+Heavyboxes It could get really messy considering the spindle air exhaust is bellow - but I should have made it clear this was for aluminium cutting although I doubt I'll be doing that much cutting to merit this. For the price I thought it was worth sharing.

+MRrwmac Yeah it would and I should look into that option as well. Maybe I can adapt the block I have into a drip? All the best to you too.

+malibuu6969 Very good - I did make one some years ago and it worked - but I just don't feel like I have the space inside. Good idea for keeping noise level down.

+Educating Savvas I understand you, sometimes we prefer to keep things simple, with no workarounds. Well, keep on updated, I enjoy your videos so much, you are in my top 5 youtubers!

+malibuu6969 Thank you kindly

i don't know about these cheap chinese clones but real industrial thing does not need cooling medium pump. air pressure creates vacuum that sucks coolant...