most of the small Britta filters (for home use ) are using weak acidic resins with some actif carbon ,this means that only the tempory hardness will be removed (the Ca and Mg bound to the HCO3) also some divalent metals as Ni,Cu,Fe ....will be captured ,this water is certainly not totaly deionised
If a total deionised water is needed a mixed bed filter is the only way or to by the so called distelled water what always means demineralised ,a membrane (RO) is also a solution
i know it quite well because i am selling those resins to all the big players and use a MB for the rinsing water (last bath ) when i develop my films (wetting agent)
most of the commercial chemicals contain complexing agents and normal tapwater (without particles ) is ok
Originally Posted by Tom Kershaw
The one I went for was the Elemaris XL, with a 2 litre capacity (£24.67/Argos).
It takes the newer Maxtra carts. which their blurb says reduces, chlorine, carbonate hardness, aluminium, heavy metals, certain pesticides and organic impurities. Note they say reduces, not removes. Anyway it sure does taste nice:).
For complete removal of impurities you would need a deioniser like the one Rob linked to. I have something similar but as I said because the running costs are expensive, the carts I use are over £40!!! I use the Brita more.
Thanks for your informative post. I do recognize that a small Brita filter system may not be the highest specification option, and I hadn't even considered Brita domestic filters until Trevor's mention. I already own one of the particle filters (the Ametek AM1), so I'm looking at the further options when deionized or distilled water is suggested or needed.
On the Brita filter: What processes are you using the Brita filter water for, and how many litres do you get before the cartridge needs to be changed?
On the lab deionizer: Approximately how many litres of water can be processed per £40 cartridge?
Yeah, at EK we used deionized distilled water for emulsion making and for chemical mixing in the lab, but here I've found that commercial distilled was good for emulsions and tap water good for processing chemistry. So, there might be a point of overkill. IDK, it depends on what works for you.
Originally Posted by Tom Kershaw
Sorry can not give an exact amount, this is because I use it for drinking water as well as mixing WS developers particularly Pyrocat-HD. Because as I posted earlier, of a white precipitate through just using tap water. This wouldn't have particularlly bothered me but when the film dried there was streaks of white 'film' on the upper surface which fortunately was easily removed with a soft cotton cloth. However since I've started using the Brita this has not reoccured.
I've never had problems with WS PMK pyro with ordinary tap water; filtered just to remove the larger particles (Paterson tap filter).
With regard to the deioniser, again I don't monitor the exact amount, because it's a colour change resin, goes from brown to red when it needs replacing. However the manufacturer states that its capacity is from 40 to 160 litres depending on water hardness. I now only use it to mix stock solutions of film developers and toners.
As Photo Engineer said, the general use of deionised water could well be overkill.
The white precipitate from the Pyrocat series is, of course, calcium and/or magnesium carbonate. Rain water or dehumidifier water will work if it's clear. Filter out the bug parts, etc. I have high humidity in the warm months, so I have a large dehumidifier. If you used a combination of borax and NaOH or KOH to get the same pH, you could probably use the tap water.
Originally Posted by Trevor Crone
As with Gainer, I collect my ac run off water in the summer time. Here in the Washington DC area, there is lotsa humidity in da summah tahm!
I have three large stainless steel chemical tanks with lids and dump the run off into them--unless I am using the run off for my house plants.
I always filter the ac water before use; use it for mixing film developer and Photo Flo final rinse. I use filtered tap water for everything else. I have no chemical problems of which I am aware, but then I use no really esoteric chemistry: D23 and DK25R are very forgiving, dontcha know.
John, Mount Vernon, Virginia USA
I just found out: 40 grams borax and 80 grams KOH or 57 grams NaOH will make a liter of Pyrocat B that works as the standard carbonate one with my Pyrocat MC, 1:1:50, 8 minutes, 70 F for FP4+ normal contrast. Should work with the other Pyrocats as well.
The ion exchange filters sold in supermarkets and hardware stores generally produce water that is chemically equivalent to single distilled water - like that you can buy in the supermarket. This is suitable for just about any photographic use. Other filters, such as activated carbon filters, simply remove grit and some organics and odors and may reduce chlorine a bit. These may not solve some photographic problems, so you should either go for distilled water or deionized water, possibly by using one of the deionizing filters. More elaborate deionizing units are available from laboratory supply houses that produce water equivalent to triple distilled or semiconductor grade water. These are overkill. In fact, tap water is fine most of the time.
Speaking of distilled water, I'm having a difficult time finding some here in London. Can anyone suggest where I should look?
thanks in advance,