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Old 03-16-2010, 05:44 AM   #1 (permalink)
johnzhou2476
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Default Understanding GH & TDS & Hardness

My TDS meter says I have 280ppm. TDS measures conductivity and pretty much everything that is in the water that is not pure H2O. GH measure only Calcium and Magnesium. When people say they have soft or hard water, they usually mean GH. So, what if my TDS reading is like over 1000ppm and no ca or mg, is that still consider super soft water? How will high TDS reading affect plant? I'm sure adversly, it could be high in sodium, organic waste, chloride, potassium, etc... In this hobby, It seems that we place too much emhasis on GH and not enough on TDS. I think more people should start measuring their TDS to get the complete picture.

So my 280ppm TDS reading consist of:
40ppm Ca
10ppm mg
35ppm K
15ppm N
5ppm P
<50ppm of sulfar


So is that consider soft, medium, or hard water? I think my GH is around 4-5 right? 17ppm of ca = roughly one degree of GH and 7ppm of mg = roughly one degree of GH?
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