RO or DI? Or is it both?

[hig789]

In the past I have always got RO water from our LFS. I am setting up a new tank after a few years away from the hobby and I have DI water available in our lab at work. From what I have read in a quick google search is that deionized water has to go through reverse osmosis first to remove the larger impurities. Just wanted to make sure this was the case and if it is suitable for a reef.

The filter is a big bottle like those used for o/a cutting torches and is computer monitored to make sure the filter is working properly.

 

[LetItReef]

Have you tried measuring it by TDS meter? Used to get RO/DI water gallon at work but when I tested it, still about 12ppm. Could it be that nobody is doing regular maintenance on system at my work.
Since then, I'm using Distilled water and always read zero on TDS meter.

 

[Randy Holmes-Farley]

While reefers and probably LFS are very casual with the terms, one often has RO (reverse osmosis) alone, deionized (DI) alone, or the combination (RO/DI).

DI does not have to go through RO first, and there are products that reefers use (such as the API Tap Water Filter) which are DI only.

The main drawback to DI alone is the cost, since the user runs through deionizing resins ten times faster than if an RO is used before it.

While a DI alone does not remove everything an RO/DI does (such as uncharged organic molecules), it is almost certainly adequate for reef aquarium purposes if it is truly deionized and I would use it if I had a ready source of it.

This has more:

http://reefkeeping.com/issues/2005-05/rhf/index.htm

 

[Randy Holmes-Farley]

Have you tried measuring it by TDS meter? Used to get RO/DI water gallon at work but when I tested it, still about 12ppm. Could it be that nobody is doing regular maintenance on system at my work.
Since then, I'm using Distilled water and always read zero on TDS meter.

They must have let the DI resin get depleted, or it got contaminated before you measured it.

 

[hig789]

Thanks for the info guys. It is regularly maintained by Culligan. I just thought about it last night while I was at work and I don't have a TDS meter. Would it be worth it to get one to check it? They take our lab tests pretty seriously, it is a good grade facility if that matters. But like I said it is monitored by a sensor that says when the filter is bad/needs changing so I would think it should be good water. Just wanted to get some opinions before I use it.

 

[LetItReef]

For me it is worth it. Check it on amazon.com

 

[Randy Holmes-Farley]

What sort of facility is it? Laboratory DI water is generally monitored very well by whoever is responsible for it, and they take it very seriously as letting it deplete could have very expensive consequences for the lab. If it is a lab, I wouldn't bother to buy a meter just to check it, as long as you knew it was DI water.

 

[hig789]

What sort of facility is it? Laboratory DI water is generally monitored very well by whoever is responsible for it, and they take it very seriously as letting it deplete could have very expensive consequences for the lab. If it is a lab, I wouldn't bother to buy a meter just to check it, as long as you knew it was DI water.

We process raw soybean oil into salad oil, bio diesel, and medical grade glycerine.

 

[Randy Holmes-Farley]

Does the DI have a gauge on it?

Often it will read in Mohms (megaohms), and 18 is very good DI water.

 

[hig789]

Does the DI have a gauge on it?

Often it will read in Mohms (megaohms), and 18 is very good DI water.

I'll have to look. All I check is a light on it that says its working correctly and the filter is still good.

 

[hig789]

Well the light is the only thing I saw. I was going to check on the lab and see if there was a gauge there but I forgot. I would assume that if there was a gauge though it would be close to the filter.

Heres a picture of the filter setup if that helps.

 

[Randy Holmes-Farley]

Given that setup, I 'd probably get a TDS meter to check it.

 

[hig789]

There are two more filters like the one next to it between the DI filter and where the water actually comes out. I'll get a TDS meter and test it out. Thanks for the help everyone.

 

[hig789]

I have a used HM pocket TDS meter and I was trying to calibrate it making a mixture of table salt and distilled water that I saw mentioned on another thread on here from a few years ago.

Everything was measured on our lab scales at work so the weights should be accurate. The distilled water came from a gallon jug from Kroger.

500.00mg of table salt
1000g of distilled water

I mixed it in a 1000ml beaker with a stirrer and a bar for about 5 minutes. And the meter read 426ppm. Shouldn't it have read 500ppm? In the thread I saw you commenting on a few years ago it stated 1mg of table salt = 1ppm in 1 liter of distilled water right? I checked the distilled water and out lab DI water here at work and they both read 0.

If this is right do I need to zero the meter out or would that just be the +/- on a cheap meter like this one?

 

[Randy Holmes-Farley]

Does that meter claim automatic temperature compensation? If not (their current cheapest one does not), then that calibration value is only good at exactly 25 deg C.

IMO, that is close enough for almost anything you'd want to do with the numbers. But if you can recalibrate it that might be reasonable, or you can just use a correction factor on all readings (multiply by 1.17, assuming you did it at 25 deg C))

Bear in mind that it is not off by a fixed number of ppm, but by a fixed percentage (assuming you made the standard exactly right and claibrated it at the right temp). If the error is 74 ppm TDS at 500 ppm, then at 10 ppm TDS the error is only 1.5 ppm TDS at 10 ppm and only 0.3 ppm TDS at 2 ppm, so where it really matters, around 0-5 ppm TDS, the possible errors are really unimportant.

There are also a variety of TDS scales widely used. Does it actually say what TDS scale? They include ppm TDS NaCl, ppm TDS KCl, and one called ppm TDS 442, which is designed to mimic natural waters. There's no simple equation to convert them at all values, but 702.1 ppm TDS NaCl = 744.7 ppm TDS KCl = 1000 ppm TDS 442.

This has more:

http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.htm

 

[hig789]

I don't believe it does have auto temp comp Randy. The distilled water was at room temp so it was probably a few degrees cooler than that. I'll just let it be. Like you said I'm sure the variance in minimal when you are talking 0-5ppm.

I tested our LFS water that I had been usin and it was at 17ppm. Probably why I have a slight algae bloom in my tank. Doesn't surprise me that it is that high really though, they are a bunch of shady characters most of the time anyways. Needless to say I won't be using that water anymore. Free 0ppm DI water sounds much better to me.

 

[Randy Holmes-Farley]

Sounds good.

Happy Reefing.