More on RO and pH

"CapFusion" wrote in message
...

"Pszemol" wrote in message
...
"Chris Gentry" wrote in message
news:gSU9e.6442$WI3.995@attbi_s71...
Again - reinventing the wheel! Please quote a single salt manufacturers
mixing instructions advocating adding buffers first and then mixing
salt...

Actually there are some salt mixes that are designed to be
used with regular tap water. (This taken from Anthony
Calfo's book on coral propagation.)

I would be interested in which one this would be...
And how do you define tap water... There are some
places where water is "hard" and contains a lot of
calcium/magnesium salts and there are different
places where water is softer, with less TDS...

The lowest TDS from tap water that I know of is from SF. My TDS indicated
about 30 - 35 ppm or so.
Water straight from the tap well very greatly from city to city and country.

CapFusion,...

That is true. However, remember, per U.S. EPA regulations, the maximum
concentration level (MCL) for TDS in drinking water is 500 mg/L. Sea Water
contains 30,000-40,000 mg/L TDS. So the TDS of ordinary tap water isn't usually
a problem. The same cannot be said for other compounds found in tap water.

George,
I don't know were you get your figures from, drinking
water at 500mg/L? I wouldn't like to drink it !! . Drinking water
should have a TSD reading of 50 or less be it mg/L or ppm (to all
intents and purposes they can be considered equal). As for sea water at
40,000mg/L !! you could walk on it !!. The sea around my part of the
world is perfectly normal sea water and has a TSD reading of 500 to
520, my artificial sea water in my tanks also reads between 500 and
520.
regards,
unclenorm

"unclenorm" wrote in message ups.com...
George,
I don't know were you get your figures from, drinking
water at 500mg/L? I wouldn't like to drink it !! . Drinking water
should have a TSD reading of 50 or less be it mg/L or ppm (to all
intents and purposes they can be considered equal). As for sea water at
40,000mg/L !! you could walk on it !!. The sea around my part of the
world is perfectly normal sea water and has a TSD reading of 500 to
520, my artificial sea water in my tanks also reads between 500 and
520.

Something is wrong with numbers above... They dont seem to be right.
How can you have only 500mg/l TDS in your sea water if you add about
35 grams of salt mix to a liter of water to make up artificial sea water?
Salinity of sea water is 35ppt (parts per thousand) and liter is 1000gram.
TDS in mg/l for sea water should be around 35000mg/l.
Many reef tanks are running with concentration of 500mg/l of Calcium
alone - what about other ions like Na+, Cl-, Mg++, SO4--, CO4-- etc?
Looking only at calcium concentration you can tell your 500mg/l TDS
for sea water is not right.

And for freshwater - maximum TDS of 50mg/l is kind of low, since
the maximum in tap water of nitrates alone is set to be 50mg/l... (mg/dm3).
Many sources of tap water have 100mg/l of calcium in it, 20-50mg/l
magnesium etc. So 500mg/l max for freshwater seems to be right number.

"unclenorm" wrote in message
ups.com...
George,
I don't know were you get your figures from, drinking
water at 500mg/L? I wouldn't like to drink it !! . Drinking water
should have a TSD reading of 50 or less be it mg/L or ppm (to all
intents and purposes they can be considered equal).

http://www.epa.gov/safewater/mcl.html#mcls

National Secondary Drinking Water Regulations

National Secondary Drinking Water Regulations (NSDWRs or secondary standards)
are non-enforceable guidelines regulating contaminants that may cause cosmetic
effects (such as skin or tooth discoloration) or aesthetic effects (such as
taste, odor, or color) in drinking water. EPA recommends secondary standards to
water systems but does not require systems to comply. However, states may choose
to adopt them as enforceable standards. (Many states have adopted them)

For more information, read Secondary Drinking Water Regulations: Guidance for
Nuisance Chemicals.

ContaminantSecondary Standard
Aluminum0.05 to 0.2 mg/L
Chloride250 mg/L
Color15 (color units)
Copper1.0 mg/L
Corrosivitynoncorrosive
Fluoride2.0 mg/L
Foaming Agents0.5 mg/L
Iron0.3 mg/L
Manganese0.05 mg/L
Odor3 threshold odor number
pH6.5-8.5
Silver0.10 mg/L
Sulfate250 mg/L
***Total Dissolved Solids500 mg/L***
Zinc5 mg/L

As for sea water at
40,000mg/L !! you could walk on it !!. The sea around my part of the
world is perfectly normal sea water and has a TSD reading of 500 to
520, my artificial sea water in my tanks also reads between 500 and
520.
regards,
unclenorm

You are confusing ppm (parts per million=mg/L) and ppt (parts per thousand=g/L).

http://www.pacificro.com/WaterCla.htm

Water Classifications

The "Glossary of Salt Water" published by the Water Quality Association
classifies water as follows:

Fresh: 1,000 ppm TDS
Brackish: 1,000-5,000 ppm TDS
Highly Brackish: 5,000-15,000 ppm TDS
Saline: 15,000-30,000 ppm TDS
Sea Water: 30,000-40,000 ppm TDS
Brine: 40,000-300,000+ ppmTDS

PPM: Parts per million=mg/L
TDS: Total Dissolved Solids

Hi George,
My apologies I retract that post I wasn't thinking
straight, it was late at night and I had just got home from a party
rather the worse for wear!!. My statement re. drinking water was
correct though I should have said it referred to RO/DI bottled water. I
still wouldn't drink water with a TSD reading of 500!.
regards and apologies again,
unclenorm.

"unclenorm" wrote in message
oups.com...
Hi George,
My apologies I retract that post I wasn't thinking
straight, it was late at night and I had just got home from a party
rather the worse for wear!!. My statement re. drinking water was
correct though I should have said it referred to RO/DI bottled water. I
still wouldn't drink water with a TSD reading of 500!.
regards and apologies again,
unclenorm.

Of course, not. 500 mg/L is the maximum allowed. But beleive me, most
municipal water supplies would cringe at the thought of pumping water with that
high a number through their pipes. And most water well drillers strive for much
lower numbers, usually below 100 mg/L, or better if they can do it. A lot of
people on well water don't have that option since they have old well, and
instead have had to install expensive filters to deal with it. Others haven't
done anything at all, and simply say "I've drank this water all my life and it
ain't killed me yet". You wouldn't believe the number of people who have said
this to me, despite the fact that what I am looking for when I test is petroleum
contaminants. I've actually had two clients die as a result of long-term
exposure to petroleum contaminants in their wells. Oh, and no apologies needed,
Norm.