High GH, KH and Low pH? - The Planted Tank Forum
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post #1 of 3 (permalink) Old 12-16-2009, 09:06 PM Thread Starter
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High GH, KH and Low pH?

Hello everyone,

After some past discussions, I decided to mix my water 25tap/75RO. I was surprised when I tested to find 8 KH and 12 GH in my tank. I do remember, however, that the pure tap was off the meter for KH, GH and pH. Or should I say, it was at the highest range for the test kits. Yes, my tap is well water. Anyway, the really curious thing is that my pH was 6.6. I have not calibrated, is that the cause or is it possible to have this pH with the KH and GH that I have?

Should I do a 10/90 mix?

A large water change is a pain because I have a 125g and my RO only makes about 25g a day. Plus, my rubbermaid is only 30g. So if I want to keep my filter running in the tank, then I can only do a 1/3 water change per day.
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post #2 of 3 (permalink) Old 12-17-2009, 03:51 AM
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It is possible to have a 6.6 pH with 8 dKH or 8 ppm KH water in an aquarium. In the first case, 8 dKH, it could be from tannins in the water, CO2 in the water, or some additive in the water. In the second case, that would be a completely normal pH, if not a little high. GH has no effect on pH.

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post #3 of 3 (permalink) Old 12-17-2009, 02:56 PM Thread Starter
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Hoppy, thanks for your response. I did a water change last night with all RO to dilute the well water more. This morning I had 6.4 pH, 6 dKH and like 178 GH (which is about 10 degrees, right?).

But I do have a piece of cedar driftwood in there. I took it from a 50 year old humanmade lake where it was already waterlogged and soaked it another couple of months with frequent water changes, then I ran it through the super hot cycle and heated dry dish washer cycle twice. My tank water is NOT brownish but I am wondering if there are tannins that are influencing the KH. Or could it still be from my well water?

Now I have been reading about KH and GH. The higher GH than KH often indicates that there is probably a decent amount of Mg, right? Do I need to dose Mg?

I have not been running the CO2 currently because I am waiting on plant packages to start my cycling. Is it possible that the CO2 isn't dissipated from when I DID have the CO2 running? There is no surface agitation. My drop checkers are yellow but I made the solution diy and have ordered some solution from SuMu because I have no confidence in my diy solution now.
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