View Full Version : water filtration for negs

Dakotah Jackson
27-Mar-2011, 12:51
Am re-doing the darkroom and looking at a Reverse Osmosis with tank system. Want a good water filtration setup in line before the RO and tank. We are on a well and very fine sediment in the water will cause problems with negative development.

Is a 5 micron filtration OK or should I go with a 1 micron size instead?

The idea is filter the water coming in(already have a whole house filter but want higher protection for my negatives) just before the reverse osmosis system and tank. Then use the final filtration the RO system provides for mixing my chemistry and for rinsing negs and prints both.

Might seem like overkill to some but have lived where very small particulate matter attached to negs and ended up feeling like fine sandpaper as a result. Don't want that possibility again. Also the RO system should help with consistent water quality from batch to batch of chemistry. I mix new developer each time for both negs and papers so I don't have old mixed chemistry laying around.

Any experience of info is helpful.

Louie Powell
27-Mar-2011, 13:22
My experience is that the only water that really needs to be filtered is the final rinse.

I'm fairly careful to allow only liquid to touch the emulsion side of my negatives during processing. So the only real issue I'm concerned about is that when the negatives dry, avoiding any kind of residue on the negatives. We have a Culligan 'Drinking Water System" to enhance the quality of the coffee and tea in our house, and I simply grab a gallon of that to use in mixing PhotoFlo.

Daniel Stone
27-Mar-2011, 17:09

try 2 filters inline. 1stly a 5micron, and then a 1micron. 5micron filters are cheaper to replace, and in the long run, will save you money not having to worry about clogging the 1-micron.

shouldn't have any affect on flow rate either, unless you already have low pressure straight from the supply line.

R/O water systems can be great, Samy's in SB employs a BIG(like 500-1000gal) R/0 system for their processing water, but just be aware that the smaller, "under the sink" units generally are designed for drinking/cooking water use. Larger units can be expensive to install and maintain, but I don't have a lot of experience with them, so I'm not an expert.

I've just found that in my processing water, having a 5micron on the supply line is enough for ME, but I mix my final rinse(for color), and photo-flo with distilled water(1gal bottles). $.85c/gal is fine, and I tend to gang up my processing anyhow right now, so it helps save water in the long run IMO.

just my $.02 :)


6-Apr-2011, 18:59
I filter all of my water using a High-Capacity Pleated Polyester Cartridge rated for 5 micron for hot and a String wound 10 micron cartridge for the cold before it goes into my Wing Lynch TC2 panel.
The cold water here is pretty clean but the hot water isn’t as clean as it could be.
I tried a sub micron .35 filter for a while, besides the expense they plug up way to fast (<2 weeks).
The 1 micron also went to fast (<1 month) so i went to a 5 micron with no detrimental effects to the film i process.
Im getting about 2 months out of the 5 micron and the cold water one has been almost completely clean for >3 months.
I use the filtered water for all of my chemical mixing including E6, C41 and B&W. Also the finals rinses and photo flo.

A great source i have found for a variety of filters, housing and plumbing is McMaster Carr.
A little expensive in some cases but no minimums and they show up the next day for me.
Btw, Kodak has published in the Z119 and a few other manuals the water quality and the filters required.

If you do want to use distilled water, i bought a water distiller off of ebay for under $100.
Its a lot easier then dragging those jugs home from the store.

Ed Brock
6-Apr-2011, 19:14
I am in my 33rd year of using rainwater harvesting for 100% of our water needs. I've had a home darkroom all of that time. Rainwater has more suspended solids than just about anything out there. I can tell you from experience that 5 microns is not small enough. I use 1 micron and use a low flow rate (around 0.5 gal / minute). A filter will last several years for me. A RO system would be way overkill to achieve the same results.

Jim Noel
7-Apr-2011, 07:19
I use a RO system. Any good system will have 2 or 3 filters in addition to the filtering membrane and they are sufficient to remove essentially all of the sediment. In earlier years I used a 5 micron filter which was good, but the RO system is far superior.