Cheap distilled water ?????

[Andy McK]

Brilliant!

or hang the kettle off your Newt's camera mount, turn on the RA drive and wait for the whistle? if it takes to long to boil, it's time to clean the mirror, and you already have some purpose made distillate

[Ptarmigan]

> robbieince> Try reverse osmosis water - available from places that sell tropical fish. Cheap and incredibly pure.

Yes. Exactly so. Use reverse osmosis (RO) if you need gallons, or condense steam from your kettle against a cold glass for cotton bud quantities.

>Gra> I would second this, but it is used for marine fish.

Umm, "it is also used for marine fish" when mixed with other salts; however RO water is used for some freshwater tropical fish such as Discus and other South American tropicals Often a pre-requisite to encouraging them to breed (/diversion

>Andy McK > hard water by definition carries alot of silica,

not silica, think u meant calcium and magnesium, Bicarbonates (hydrogen carbonate) easily removed by boiling and cooling ("temporary" hardness). And Sulphates, ("permanent" hardness) which need distillation (or evaporation and freezing or RO) to remove.

"deionised" as sold by motor factors is produced via ion-exchange resins and can contain acid (usually) or sometimes alkali remains of the resin reconstitution/recycling processes at end of life production cycles. There is also a "deionised" process that leaves a high residual of common salt (sodium chloride) but I dont think motoring sources use that.

Stay with RO or true distilled.

[BazMark]

Do you know a window cleaner that uses a Water Fed Pole? Most use RO + DI water? That combination produces zero dirt (TDS) in the water provided they keep their filters maintained which most would as it's their living. They would probably spare you some

[spaceboy]

The RO water sound a winner so will pop in A&D aquatics next time I'm passing to see how much it is. Thanks for the info guys

[LukeSkywatcher]

Well, what I could do, in the interests of science, is try several brands of Vodka from expensive down to the Li**L brands, document the results and report back..

I look forward to your report.

[Ptarmigan]

The RO water sound a winner so will pop in A&D aquatics next time I'm passing to see how much it is. Thanks for the info guys

Good call !

There is a recurring problem in all these sorts of discussion - water supplied for one purpose may have a similar vernacular but poor description for our purposes :

window cleaners are not concerned with aluminium coatings, thus alkaline (sodium hydroxide) residuals in anion exchangeDI are of little concern to them !

Similarly cation exchangeDI may contain hydrochloric acid residuals which will not affect the aly coating but may transport, by capilliary, other undesirables from adjacent structures depending upon hygene !

Combined anion/cation DI excange resin processes - well anyones guess what the residuals are !

However, another consideration is that vendors such as Halfords are supplying the motor trade, not astronomers !, consider that their description of "Deionised water" is adequate for its intended purpose (lead-acid batteries), but that may be an historical description, these days RO is much much cheaper than DI, so it may be that they are supplying RO but calling it DI ????

but why take the chance !

[perrin6]

I use reverse-osmosis water from an aquarist and much cheaper than distilled. You take containers with you and fill them yourself in some places. Aquazoo is one place.

[blinky1983]

be careful there is de ionised and there is distilled, de ionised will leave streaks on optical mirrors

I use de ionised water and its great, no streaks at all..

[dave6666]

Hi try a good pet shop that sells salt water fish as you need to top up the tank with distilled water you might get it free as you don't need much or try and find a window cleaner as some use it now for windows