View Full Version : safe to use 13 ppm RO water?
nemofish2217
02/06/2010, 12:46 PM
I filled a bucket with fresh RODI water for a water change. Well, I tested the water in the bucket with a TDS meter just because, and it read 13ppm. I then tested a separate little glass of fresh RODI water and it tested 0ppm. Is it safe to assume that the reading is because there might be some residual salt or something in the bucket from last week's water change? The bucket has had nothing in it except saltwater... 13 ppm would probably be okay regardless, right?
Any thoughts?
surfjeepzx
02/06/2010, 02:32 PM
my tds meter is up to 17 and my tank is fine. It's been slowly creeping up as the DI resin is starting to change color. I've had the tds read in the upper 20s before changing the resin and filters. No negative results and no observable improvement once it was at 0 again.
jarrett shark
02/06/2010, 04:21 PM
some TDS meters need water movement to work on there probes
if it a inline tds meter then 13ppm is wrong.
Buckeye Hydro
02/07/2010, 07:59 AM
If your bucket was something other than ABSOLUTELY clean, you'll never see 0 tds in a measurement there.
Russ
jhutton
02/07/2010, 08:02 AM
i am sure its better than tap water which is 180ppm where i live
but i change my filters when i start to read 1ppm
Nexenn
02/07/2010, 08:17 AM
NEVER check TDS in the bucket as they are always wrong. Test it in line or like I have, check it in the 30 gallon trash can you make it in. If you've ever used the bucket for anything other than transferring fresh RO/DI water in it then its the bucket. If you make fresh salt water in it and use it for a water change the left over salt residue will through your TDS up. My buckets always read ~25-50 even though my RO/DI is really 1ppm and since you tested your ppm another way and it showed normal goes to show its fine.
Buckeye Hydro
02/07/2010, 09:13 AM
From our FAQs:
In this hobby we measure Total Dissolved Solids in parts per million, or "ppm." We often try to measure TDS down near 0 ppm. Because this TDS level is so low, we have to keep in mind the sensitivity of the meter used to measure it, and the technique used to measure the tds.
Nearly any contamination in the sample container will cause an erroneous TDS measurement. Some plastic containers are difficult to get absolutely clean, and although they appear clean, they are not. An easy standard approach is to use a drinking glass as a sample container - use one right out of the dishwasher. Obviously, keep your fingers away from the inside surface of the glass.
Calibrate your meter. Use a calibration fluid generally in the range of the tds measurements you'll be taking. Some meters require a specific tds calibration fluid (e.g., 800 ppm), regardless of the tds levels in your samples.
Be careful with how you take your samples. Let's say you intend to measure the TDS in your 1) DI water, 2) RO water, and 3) tap water. Start with the cleanest of the three - the DI water. After letting the system run for a sufficient period of time that you are sure the tds levels have stabilized (to assure you are not measuring tds creep water), rinse the sample container two or three times with the water you intend to sample, and then fill the sample container with sufficient DI water to take a reading.
Now on to the RO water. The water we are interested in here is the permeate – i.e., the water that has been purified by the RO membrane – not the waste water. Make sure you understand which is which before taking the sample. Most RODI systems other than Buckeye Systems are not plumbed to facilitate taking a sample of the permeate. If that is the case, you’ll need to unhook some tubing – likely where the tubing attaches to the “in” port on the DI housing in order to take this sample. This is inconvenient for many people, and we find that people never do it. They report only the tap water TDS and the DI water TDS. Contact Buckeye if you need guidance regarding installing a couple of extra fittings and tubing to facilitate measuring the TDS of the RO water (permeate). When you take the sample, follow the same procedure described above – use a clean sample container, assure you are not measuring TDS creep water, rinse with the permeate several times before taking the sample, and use a calibrated meter.
Use the same approach to collect and measure your tap water as well.
radicaltimes
02/07/2010, 07:37 PM
Mine is 0 leaving the DI unit and measures 20-30 TDS after a couple days in my container.
Matt Wilkie
02/07/2010, 10:29 PM
lol my Tap is always under 20 and my bucket will read 0 for along time, RO/DI doesn't need to work that hard when its that low. Benifit of living in British Columbia.
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