Water Hardness: Expetations

shoe

shoe

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Sep 25, 2006
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Wondering how to determine that my RO/DI system is producing good water.
In this I bought a PINPOINT Hardness meter.

Straight from the tap, how should the meter read? <-- Yeah to hard to say!

After the RO process?

After the RO/DI process?

Looking for measurements in microSiemens (µS) but both Parts Per Million (ppm) and General Hardness (dH) are good too.

(The conversions are 33 µS=17.9 ppm=1dH...)

And if you have a link to 'somewhere' that spells this stuff out, will appreciate you passing it along... Thanks!
 
shoe said:
Straight from the tap, how should the meter read? <-- Yeah to hard to say!
Click to expand...
That really depends on your location, and even then, it will fluctuate quite a bit.

After the RO process?
Click to expand...
Depends. What's the reject ratio of the membrane in the R/O? In a perfect world, the answer of course is zero. But there is no such thing as a membrane with a reject ratio of 100%.

Purity is determined by two things: The reject ratio of the membrane and the type of salts in solution.

A 95% reject ratio means that 5% of the salt concentration leaks through so a 200 PPM input stream would result in a 10 PPM output stream. A membrane rated at 99% would result in a 2 ppm output stream.

The reject ratio will decrease as the membrane ages.
 
Ratio is 3 to 1 - unit claims to remove 99.9% of contaminates:
(Kent Marine / Maxxima Hi-S 60 GPD)

That's an interesting approach to take regards 200 to 2ppm if the filter is 98% effective.

I suppose in my case, 200ppm translates to 0.2ppm, seemingly unrealistic.
 
I'm in line with your opinion however, must ask...
Are you claiming 'beyond doubtful' out of principle or because you know?

Reason is, Kent Marine offers a variety of filters some apparently EXCXEEDING 99.9 % purity:

Maxxima (MAX24, MAX50) will remove over 99.9% of tap water contaminants, providing 18 megohm-cm lab grade water...

Maxxima Hi-S(MAX35HiS, MAX60HiS) will remove 99.9% of tap water contaminants, providing lab grade water...

Maxxima-R (MAX24R, MAX50R) will remove over 99.9% of tap water contaminants, providing 18 megohm-cm lab grade water...


Alas, mine is in the middle and ONLY removes 99.9% or so they say:)
 
Clever marketing, actually.

What they are doing is counting the overall unit, including the pre-filter that removes suspended particles, and they are also obviously counting the removal of the chlorine as well.

The RO/DI units can and should reach 99.9%.

I was referring to the efficiency of the membrane, since that's what's we are interested in within the industry. The best membrane I can supply is a 99.75%, but those cost a bloody fortune. A replacement membrane runs them about $850 installed. When new, it may exceed the rating for a while, then it will begin to fall. No big deal, because the RO water is further processed anyway. We use those for the Medical and Research Lab units.

In order to get the purity they want, we go through carbon filtration, then through ion exchange resin, then through the three stage RO, then through the DI unit.

For research, it makes sense. For an aquarium? No thanks. I don't like wild pH swings personally.
 
I meant to ask, but forgot to...

Why do you want to use RO/DI water in an aquarium?

I know that a lot of people who keep reef tanks use it, but the first thing they they do is add their marine "salt" to it. In other words, they are starting with a clean slate and adding just the minerals and trace minerals they want.

In a freshwater tank, you will be adding water that has virtually no buffering capability. This can result in the pH taking a dive, so watch for that.

My water for the tank goes through carbon (synthetic actually), then through ion exchange, then through an RO. But I have a bit of crushed coral in my filter to buffer the water a bit. This seems to keep everything stable.
 
You may be interested in the membrane only but I'm interested in the final water quality. Not sure how that is clever marketing when they're not selling a membrane but instead a complete system (at least regards the links I provided).

So why did I go RO/DI?

I suppose because I heard so much crap about water quality - both for and against 'pure' - that I just got tired of it and figured I couldn't go wrong if I was absolutely sure I started with pure (plus the family benifts from the RO unit).

But also I had it in mind to run a DISCUS tank (which I did for a while and will probably do again).

So yes, I add 'stuff' to the water during partial water changes to restore hardness and trace minerals and yes I have to watch pH, especially since I run soft / low pH water (cuz of my preference for Cardinals).
 
Ah, so basically, you're doing the same thing as I referenced with the saltwater guys - starting with a clean slate. It does eliminate a lot of variables when you know precisely what's in the water because you are the one who put it there, and you know it's nothing potentially harmful.

As far as the marketing thing goes, to tell you the truth, I really never paid attention to how this equipment was marketed to the public. The people I deal with on this stuff already know what the pre and post systems are going to do. The only thing they care about is the membrane, since it is more of a variable. So from that point-of-view, it seems downright deceitful. Please keep in mind, that is the viewpoint from a totally different aspect of the industry.

The system you bought looks very nice. I especially like the color change indicator on the DI to keep you informed.

You should see some extremely low numbers once you get it set up, if it isn't already. The first little bit may not be perfect, but after everything is fully saturated and the lines get cleaned out I wouldn't be surprised if it produced water below or barely over 1ppm.

What I was referring to in the last paragraph is that there will be a certain amount of contamination in the tubing, etc that will rinse out as you run water through it. Even some of the chemicals and releasing agents, etc from the manufacture of the tubing may show. Normally, they would not even be a factor, but with as clean as your water is going to be, you may actually see it with your meter. Along the lines of one drop of food coloring in a lake can't be found/measured, but a drop in a shotglass of water will color the water a lot.

So if the initial production isn't what you expect - give it a bit of time. The more you use, the better it will get.

Oh, and by the way - are you a coffee drinker? Use some of your RO water to make a pot of coffee. If you're used to hard water, you may be amazed at how much smoother the flavor is.
 
Appreciate you reply... By the way... How are you affiliated with the 'clean water' business?

And yes absolutely right (for me) that I got to a point of obsession regards starting out with water that's pure... Didn't start out that way of course... 10-gallon tanks and tap water (with drops) go hand in hand:)

I've had the unit for a few years now so I'm quite used to RO coffee and my lines should already be clean:)

But I didn't concern myself with electronic measuring equipment since the 'experts' I talked to back in the day thought them too much trouble.

In addition since I knew, or believed I knew, that my my water was soft, I didn't concern myself with hardness and instead concentrated on pH.

I had some fish trouble recently and because my filters required replacing AND because someone recenlty convincenced me to pay more attention to hardness AND because I had it up to 'here' with chemical tests AND because I've been working so many hours (ie more cash in pocket), I decided to buy an electronic Hardness (and pH) monitor.

I was definitely suprised by my first tank readings especially hardness as it appeared I used way too much "Reverse Osmosis Reclaim Chemistry" (ie, Kent Marine RO RIGHT) and even now am in the process of reducing hardness. (Quite odd eh? I suppose it could be compared to the driver who becomes lax of speeding tickets just because he has a radar detector.)

So now that I've invested in my gadgets AND have replaced my filters just want to get a feel for various readings I should expect along the various stages of water purification...

I'm a little miffed though about the monitors, especially the pH monitor since it is recommended I calibrate the probe every month and replace it every 18.
 
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