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GH and KH Question


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I recently watched Irenes video on PH, GH, and KH and I would love to know more. How important is GH and KH specifically? Based on the video I assumed that you either have low KH and GH or high GH and KH since the solution for lowering these is less water changes or to increase them is to add crushed coral

I tested my water and see to regularly have a extremely high KH (300 ish) and extremely low GH (0-40). 

Question 1: Are these parameters of for my plants and fish? I have dwarf petricola, orange shrimp, exclamation rasbora, and mystery snails. 

Question 2: How do I lower the KH and also increase the GH? 

More info on the tank. Its a 12 gallon planted tank, with a PH of 6.8~ and I inject CO2 at a rate of 1 bubble per second. No recent water changes have been made. 

Thanks for helping me understand this better. 


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GH is a measurement of dissolved magnesium and calcium ions. Low GH = “soft water” but high GH = “hard water.”

KH measures carbonates and bicarbonates. This relates to “buffer” in relation to pH swings. Low KH = low “buffer” = potential for sudden pH swings, especially as humic acids build up from plant and food breakdown.

I think that dosing CO2 can slowly break down your buffer (i.e. lower your KH).

My recommendation to any aquarist is to try to live with the water you’ve got rather than to fight against its parameters. Only in certain circumstances — e.g. someone trying to breed Discus — would I recommend installing an R.O. System, and then adding chems to your desire afterwards. 

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