560ppm going into the RO/DI 30 coming out
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AZDesertRat
In Memoriam
627 Tap, 13 RO and 0 DI here in Phoenix. I use a handheld TDS meter and will trust it before I would and inline meter that I cannot clean or calibrate. Its the treatment plant operator coming out in me, you have to test meters constantly if you want accuracy.
anthworks
New member
I have two meters that both give different #'s. I take either meter put it into a test sample to get a reading if I remove and test again I get a different TDS #, I could test the same water 10 times and get 10 differnet readings. Its sometimes higher sometimes lower. I get a jist of my TDS by an average of all the different readings. If I am below 30 TDS I feel I am fine since I dont have any bad algea and everything looks good.
AZDesertRat
In Memoriam
Its very possible to get different readings from the same meter. Once you dip it in and pull it out you have changed the electrical conductivity of the water. Air, dust, your breath, anything can change the conductivity.
landragon
Premium Member
It could be off and read low. Say it is off by 5 points or it is within it's stated 2% variance. This is bad news for most meters. If the scale is wide, the 2 % is a larger number. I usually try to calibrate the inline ones to new DI resins effluent after it has run 1 hour. I set it untill it goes just over 0 and then back it a hair till it is 0 again. I know this is not scientific but seems to work ok. Still the scale is so broad on these, that the variance CAN be 80 tds. Not that it will be, but it can be. And the meter is considered to be fully functional then too. If you are worried get a Hanna PWT and use it occasionally to test the inline. If you are really worried, get a Hanna UPT. Those are crazy accurate. But overkill ceretainly for most of us. The PWT is notmuch more than a decent inline and way outperforms it for accuracy. all IMHO of course. By the time most inlines read one , silica has been streaming from the resin IIRC for some time. Therefore, it is also advisable to get a second DI stage, and run the meter after the first. As soon as it reads 1, chuck the resin, rotate the resin, and replace the second stages resin. But I am a control freak and sometimes have the money to burn to figure all this crap out for my situation.
I recently tested water with 0 ppm just to verify the accuracy of my inline meter. Both lines tested perfect. So my initial readings are correct.
Testing the DI filter (yes I have one): The instructions indicate that running unpurified water through the DI without going through the RO section will damage the filter. So how do I test?
I noticed that initially the water comes out of the unit at 30ppm but 15mins later it declines to 23ppm. Is this normal?
I donââ"šÂ¬Ã¢"žÂ¢t have a softener (and no I donââ"šÂ¬Ã¢"žÂ¢t drink the water LOL). But I think it's time I invest in one. I had no idea that softening the water would reduce the tds in the water.
landragon
Premium Member
Yes it is normal for a r/o membrane to produce better water after several minutes of operating. Softening the water indeed reduces tds, but not in a neccesarily positive way for reef tanks. The sodium ions left over can build up to toxic levels over time IIRC. Sodium softened water must be put through a r/o or di filter before being used for aquariums. Running unpurified water will not " damage" DI , it will however exhaust it very quickly. It renders it useless rather soon.
AZDesertRat
In Memoriam
I recently installed a water softener and have discovered it didn't reduce the TDS at all. What it did do though is change the components of the TDS to things more manageable for the RO to remove. Calcium and other hardness causing minerals are now sodium which is a breeze for RO membranes to reduce. It did increase the efficiency of the RO by a point or two, my raw water TDS is still in the 620 to 640 range but my RO only product water went from averaging 13 down to 10. DI is still at 0 and I just changed the resin so I am going to calculate how many gallons I get per 24 oz. refill now. I have been getting right at 250 gallons so maybe I can now get 300?
smleee
New member
Softeners do tend to raise your TDS, but essentially it's doing all the "hard work" (pun intended!) by taking out the tougher dissolved solids but replacing them with your softener of choice. TDS doesn't tell you what's in the water, just how much. Think of it as "at lot of bad stuff" vs. "a lot of not so bad stuff".
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