Kshack Posted May 4, 2010 Share Posted May 4, 2010 I have been trying to get my PO4 levels down from .06-.05 to the recommended .03 levels for some time now. I purchased a Hannah meter 9 months ago. Yesterday I decided to try testing my RO water. Made sure my sample was 0 TDS (new DI and let it run for a few minutes). Took three samples and the average was around .10. Thought my meter was defective and was thinking of sending it back. Took a sample direct from faucet and the number was .64. Then took a sample from my tank and it was .04. So my meter looks like it is working properly, but I am confused about my RO water being so high. Couple observations....With the fresh water tests, I noticed a very fine film of bubbles on the inside of the glass vial. Could that be the cause for the high numbers? Does this test not work well for fresh water? Is it possible for a PO4 of 0.10 in TDS "0" water? I tried to clean the inside of the glass vial. Used rubbing alcohol in one and vinegar and rubbing alcohol in the other. Could this be the cause of the very fine bubbles and strange numbers? Anyone know this meter well enough to guess what is going on? Quote Link to comment Share on other sites More sharing options...
madmike Posted May 4, 2010 Share Posted May 4, 2010 I have the meter, you have to not "shake" the vial after you add the powder. I just kind of roll it back and forth in my fingers so no small bubbles appear but the powder dissolves.... it takes about 2-5 minutes for the powder to dissolve. If your phosphate is really low all of the powder doesn't all have to be dissolved. Then give the glass a good clean swipe with a lint free towel and put in the meter for a "timed reading". This will allow everything to settle and give you the best results. I have found that testing on the low end requires precise attention to prep of the test and an ultra clean vial. Any scratches or smudges on the vial can ruin tests so make sure your vials are clean and scratch free. It is possible for 0 tds water to show phosphate if your meter is faulty. How are you testing the tds of the water? I have a spectrapure 180 gallon/day unit and the inline units show 0 while my HM digital COM 100 will show upwards of 1-2 tds. Quote Link to comment Share on other sites More sharing options...
Kshack Posted May 4, 2010 Author Share Posted May 4, 2010 I do not shake the vial, but swirl it for 30seconds, then let it do the 3 minute read. Should I swirl longer? The TDS "0" is from both an inline meter and a handheld meter. I do wipe with a lint free cloth, but there are some minor scratches that were there when the unit was new. Quote Link to comment Share on other sites More sharing options...
madmike Posted May 5, 2010 Share Posted May 5, 2010 if there are scratches, I personally would replace the glass, light has to pass thru the glass and any scratches will skew the results. Are both glass vials scratched? You may need to swirl longer, my phosphate measures 0.01 at most times and it takes at least a couple of minutes for most of the powder to dissolve. I have tested others tank water with much more phosphate and the powder dissolves much quicker. Quote Link to comment Share on other sites More sharing options...
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