[b4u]

i bought some r/o water from a local aquirium. when i get home i decide to test the water for the hell of it, i used mardel ammonia test strips. the ammonia lv was at a 3.0 ..... now my question is did i get ripped off, or does r/o water not remove everything?

[Lazy Iguana]

R/O is supposed to remove a lot of stuff. But the filters do go bad eventually. When the membranes go bad they stop working.

Someone could have made a mistake and collected the waste water and not the filtered water.

The test strips could be contaminated. You can test them with a gallon of DISTILLED water from the supermarket. Distilled water should have nothing at all in it. Not even a Ph. Nothing. Distilled water is pure water that does not really exist in nature. Even rain water will have something dissolved in it by the time it hits the ground.

If your test strips show anything in distilled water, the strips are bad. You can find distilled water in the supermarket by the gallons of drinking water. You can drink distilled water, but it tends to taste "funny". But I am used to it so no big deal. I sometimes use the stuff to make coffee.

If I bought a home unit, I would get a R/O filter with a deionizing filter.

[b4u]

yeah i'll check that out , thanks

[dhboyd1]

Distilled water will have a normal PH of 7.

[dhboyd1]

BTW, always test water from your LFS until you trust them. I bought 50 gallons of reef RO/DI and when I got home the salinity was 1.016. OK for fish only but sucks for reef tanks. I am glad I tested.

[Lazy Iguana]

Actually distilled water has no PH. Not 7.0, not 1.0 and not 13.0. It has no PH at all.

Testing for PH in distilled water is like testing for oxygen in the deepest vacuum of space. You will not find any.

Most PH kits will register the lowest PH value for distilled water. But is is not acidic or basic. It is whatever you want it to be.

OT have a PH something has to be dissolved in the water. True distilled water has nothong but hydrogen or oxygen in it. No ions = no PH.

[dhboyd1]

If it doesn't have a Ph then it isn't water. Ph is the measure of acidity or base. A Ph of near 0 is the most acidic substance known to man and a Ph of 14 is the most caustic.

To quote from Chme4Kids.com

"pH focuses on concentrations of hydrogen ions (H+) and hydroxide ions (OH-). The scale goes from values very close to 0 through 14. Distilled water is 7 (right in the middle)."

Since water is made from 2 H atoms and 1 O atom there will always be some ionization from background radiation so distilled water will only be at Ph of 7 immediately after distilling. Usually it will drop after sitting for a few moments.

Check your chemistry books.

[dhboyd1]

BTW, the actual representation in pH. And any solution with a pH of 7 is neither acidic or basic but considered neutral. If you want the complex explanation of pH wiki it.

[Lazy Iguana]

Strange. You say it is 7.0 (neutral). But when I test it for Ph it registers no color change. I am using a freshwater kit where yellow is acidic and blue is base - green is neutral. Distilled water shows yellow. Very yellow. According to the test kit, it has the same Ph value as vinegar.

It is only after I add some 7.0 buffer that it tests green. This could be due to some atmospheric CO2 getting dissolved in the water during the bottling process however. But really I think it is due to the lack of ions in the water. It fools the test kits.

Or, it has no H or OH ions in it. You can call this neutral, but because this is an unnatural state for water to be in, Ph really has no bearing on distilled water. Any test is going to be misleading. Neutral naturally occurring water has ions dissolved in it. Distilled water has nothing dissolved in it.

[dhboyd1]

Most test that test for all pH conditions are extremely inaccurate. In the laboratory, testing is done at intervals using different chemicals for each interval. The test kit I use only test the interval of 7.4 to 8.6 which increases the possibility of it being relatively accurate within that range. I would be very suspicious of any test kit that shows distilled water at the same level as vinegar. The basic fundamentals of chemistry don't change because an inexpensive test kit says they are wrong. In a vacuum distilled water has equal H+ and OH- ions but nothing to react with. Since most distilled water isn't in a vacuum it will show some acidity because of CO2 in the air. The actual pH of distilled water is 6.995 but since most kits aren't that accurate 7 is the agreed upon pH of pure water. The relevance to most in this hobby is pure water is the base line test for your test kit. If your test kit doesn't show a pH near 7, ammonia of 0, nitrites of 0, nitrates of 0, phosphates of 0, calcium 0, for distilled water then you should question your water source or your test kit not the fundamentals of chemistry.