tds reading on distilled water?
 

i was just wondering if distilled water has a reading of zero using distilled.i am asking because i think my tds meter is flawed or something because my reading is like 20 with a new di resin and carbon and sedimen filters.the membrane is only a year old and i dont have a hugh demand on it,thank you for your replys.

How much water has been run through it? You could try calibrating the meter or testing it with a calibration solution. 20 ppm seems fairly high for fresh RO/DI water. What is the TDS of the tap water?

Distilled water is hard to judge. I don't think it'll make a useful standard.

maybe im sticking the unit down too far in the water or something.lets say i put the meter down a 1/4 inch it says 7 to 8,when i push it down further it ll say something like 20,my tap water is 160 ish thank you for ur time.its weird because most of my filters are new,all i use it for is a 10% weekly water change and top off thats not too much demand i dont think.my system is about 150 gal total.

just finished testing again.my readings are 13 on the r.o. and 140 on the tap water ,what do ya think.if i need to calibrate does anyone have a homemade solution or can i buy it.from what i hear its sodium cloride.

what does a sample of the RO ouput (before the DI resing) read?

Your RO unit should drop your TDS by at least 98%. If it is not doing that, then it's time for a new membrane. The DI resin should then take it to zero. If you are putting out 13 TDS on your RO unit, you're going to burn through the DI resin pretty quick. If that meter is right, your membrane is shot.

Distilled water, by definition, will always be 0 TDS. Distillation involves taking a liquid (water) and converting it to a gas (water vapor) then condensing it back to liquid (water again). You can't dissolve a solid in a gas, so there are no dissolved solids remaining after distillation.

There are no carbon or sediment filters or DI resin involved in distilled water. If you really mean to ask about RO/DI water, then you may very well read some TDS for the first few minutes of operation or the first hour or so after replacing the membranes.

Jeff

A statement by Randy regarding distilled water from this thread:

Distilled Water
http://www.reefcentral.com/forums/sh...istilled+water

Randy's statement:

"One cannot give a blanket OK to distilled water.

The answer is going to be related to the exact nature of the metal cooling coils used, and whether they contain substantial copper. There can be too much copper from distilled water."

I would suggest using certified pure water or perhaps the pure water sold for calibrating refractometers for checking the calibration of your TDS meter. :)

Would a test kit for copper sold for the aquarium hobbyists be a valide tool to detect if the distilled water is free from copper?

Not for very small amounts. A few parts per billion of free copper can be harmful to invertebrates.

The recommend high concentration in reef water for copper is only 30 parts per billion. That's not much. The hobby grade test kits can't detect copper much below 100 ppb. For some coral and reef occupants, copper causes problems as low as 10 ppb (& some research is finding levels lower than this can be a problem for certain coral). The form that copper takes in the reef tank makes a big difference. When copper is tied with dissolved orgnanics it is much less toxic than when in the ionic form which is what you find in salt mixes and many chemicals used to add copper for treatments of parasites....etc. ;)

Your filter is not working. The output from the RO phase should be more like 3 ppm, assuming the meter is correct. I'd calibrate the meter or get a second opinion to be sure, and then work on the filter. The membrane might not be seated properly, for example. To be sure, you should produce about a gallon, at least, of RO water, and throw away the first half gallon. The membranes often leak while sitting idle. You could try the water after the DI phase, too, but I think that the cartridge is shot.

Distilled water isn't necessarily 0 TDS, for a number of reasons. In addition to contaminants from the coils and after the fact, carbon dioxide can raise the TDS, and distilling will leave some other contaminants in the water as well.

thanks for everyones replys ,i wasnt gonna use distilled on my tank,i just wanted to see if my tds meter was reading correctly,and im not too sure of what calibration solution to use.my reading could be alot lower if i can confirm that my meter is accurate.i just need to calibrate my meter for peace of mind. thank you.

what do u people use.do u buy it or make it.thank u.

You want the 342 solution.

Try Buckeye Field Supply
From a previous post:
" We have 342 ppm, 800 ppm, and 1382 ppm calibration fluid.
Russ @ BFS "

342 should be okay. You could also try a lower ppm solution if there's one available. It might give more accuracy.

I agree with redfishblewfish and would check the output before the DI unit. I just do a quick PH test on mine.

i tested about 25 gal of distilled water from different source and they all read zero...

Your disstilled water is fine they dont use copper pipes anymore, that old info from about 20 years ago. I have tested so many gallons of distilled water and was all zero on the tds meter

I agree that copper is very unlikely, and that distilled water is fine to use in a tank.

Good to hear that distilled water ok to use. Cause I had use it before I got mine rodi unit.