The Planted Tank Forum - View Single Post - Urgent! Kh and gh issues
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Old 01-30-2013, 01:17 PM   #14
danielt
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It is impossible to have no gH change if you did a 50% RO water change. Check your test, check your measuring process. You're doing something wrong. Stones cannot increase water hardness quickly, there is a slight hardness increase over time. In days or weeks, not several hours.

If you have a TDS meter. Test the RO water with it, test the aquarium water. Compare, do another 50% change, test again.
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