Quote:
Originally Posted by Natureman
I was using those cheap $8 TDS pen. It was ok for 2 yrs then it stopped working. Replaced new batteries also not working. The last reading of my shrimp tank water was 140 ppm with this TDS pen before stopped working. Then I bought a new one of the same China made TDS pen. And was surprised the reading with the new pen was at 95 ppm, very different from 140 shown by the old pen. 95 ppm is too soft for prl shrimps. That may explain why the shrimp population not increasing! So becareful of this China made TDS pen, may not be accurate after sometime
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best way to check if TDS pen working, go and use it on distilled water, should be 0 or close to 0.
95ppm is still okay, but what i feel optimum is 100-130