Ph level of water from faucet and RO system

[pepeguitarra]

Hard water is alkaline water. There is a trend now to drink alkaline water, they sell machines that create alkaline water and sell for a lot of money. Some of the same people who has a treatment water system at home (softening+RO) usually buy the alkaline water machine (when they could have drank the hard water in the first place). Usually softening (removing of Calcium and Manganese) is done before the R.O. because membranes cannot handle removal of Ca and Mg too well without clogging. The problem is that softening is done by a process called ION Exchange (IX) in which salt is added to exchange and replace Ca & Mg with Sodium. Those salts are later eliminated creating a high concentration of salt in the sewer, rending the sewer impossible or very expensive to be reclaimed and recycled. That is why water softeners are banned in many areas of California. By removing the Ca & Mg, the water becomes acidic. That is why when some people use it for stop bath, it works. I have not studied the effect of an alkaline developer will have on the water itself. I guess that using hard water (alkaline water) may accelerate the development time of film. Will you have to reduce the developing time? I am not sure of this, but I will look into it.

PS: Most home salinity removal system sellers do not tell you what is the TDS (total dissolved solids or as we have been calling it ppm) in the final water. Some buyers think they are getting 0ppm, which is impossible for health purposes. I will be interested in hearing what is the TDS of the water at the faucet (in ppm or mg/L).

[Steven Ruttenberg]

Mine is 440ppm at faucet 22 after RO. Water at faucet is slightly base about 7.4 out if RO 6.4. I am considering switching to potassium system

[pepeguitarra]

With TDS at 22 ppm, the water must taste really good, you must be saving a lot in soap. In the best days, I get 500ppm at the faucet, I don't have RO, I worked for the water district and trust my water, so I drink it straight from the tap. I usually buy Distilled Water from Walmart ($0.94/gal) for mixing my chemicals. I wash the film with tap water, but the final wash with kodak flow is with distilled water. Whenever I run out of Walmart water, I used tap water that has gone though the refrigerator, just because it removes some of the residual ammonia. I don't think switching from sodium to potassium will make a big difference, Potasium (K) and Sodium(Na) have the same valence in the Periodic Table, remember (K, Li, Na, H, Rb). You may want to try a test using the water delivered by the water company (440 is not bad), the water will be alkaline and maybe more stable with the developer. Disolved solids will not probably react with the silver, so I don't think there would be a reaction there. And because the TDS is DISSOLVED solids, they will get out with the final wash, not stay on the film.

[Steven Ruttenberg]

Good discussion. The water at my work where we use environmental chamber with heat and humidity has 220ppm and it destroys the little brass bowls and fittings. Nasty deposits. I just tested it.

The water from RObtastes awesome. In fact, my wife will not drink any other water, even if she is dying of dehydration. Short of distiller, I doubt I can get less ppm. I will see this water to mix developers and rinse with tap water. Photoflo I use the RO water as well.

I suppose I could treat water to raise the ph level to 7 before using it for mixing chemicals.

[pepeguitarra]

I think the recommendations by the manufacturers has to be strict and done based of neutral water, etc. However, after a while, we learn that those temperatures, and exactness on the solutions can be approximate. For example, I found out that one 35mm roll, one 120mm roll, and one 4x5 sheet of film will use 3.5 mL of rodinal for stand development. So, what I do is put in a tank 4 or 6 sheets of 4x5 (mixed up, e.g., Kodak 100Tmax, delta 100, Max 400, etc.) and pour a solution that has 3.5x6 sheets (21 mL) of Rodinal, and the remaining (979 mL) of distilled water (or water from the fridge) (I use the Jobo tank that has a full capacity of 1,000 ml to cover the 6 sheets). I don't measure the temperature, I know is around 62-to 72F. I agitate for one minute and let it sit for as long as I can. I try to come after one hour, or two, or three. One day, I left it overnight. Come back, fix it, wash it and done. They all come back just fine.

[Leigh]

I found out that one 35mm roll, one 120mm roll, and one 4x5 sheet of film...

Those are not equivalent.

Equivalence is whatever you can proof on a single 8x10 sheet of paper.
So it's one 35mm roll, one 120 roll, or FOUR 4x5 sheets.

- Leigh

[pepeguitarra]

Those are not equivalent.

Equivalence is whatever you can proof on a single 8x10 sheet of paper.
So it's one 35mm roll, one 120 roll, or FOUR 4x5 sheets.

- Leigh

I stand as corrected. Thanks.