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Discussion Starter · #1 ·
Using the API tests to check my tap water, my KH is 10 and my GH is either 0 or 1 (changes color with the first drop). I bought some GH booster to raise my GH. I've read in a few places that you should match the KH and GH, but is it really necessary to get my GH up to 10? I'm not sure what the benefit of matching the KH and GH would be. I'm assuming that getting the GH to about 6 would be sufficient? Also, since 3/7 of the GH booster is potassium sulfate, would I still need to dose additional potassium as a fertilizer? Thanks.
 

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3-5dGH is enough for good growth with most plants and values do not need to be matched in ratio GH/KH LOL.
 

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Isn't KH a component of GH and the therefore always a lower value?
Not necessarily. When you add baking soda (Sodium Bicarbonate),
Potassium Carbonate, or Potassium Bicarbonate, etc. You only
raise KH. In nature, the Calcium might be precipitated out somehow,
leaving more KH than GH.
 

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Discussion Starter · #7 ·
3-5dGH is enough for good growth with most plants and values do not need to be matched in ratio GH/KH LOL.
I figured as much, but like I said, when I was researching I found a couple of sites that recommended matching them. They never gave a reason though, so I don't know why. Since the GH booster raises in 3's per tablespoon, I'll just aim for 6dH.

Are you sure your gh test kit is working correctly?
I believe it is. Back when I was using test strips they told me that I had a high alkalinity, but like no general hardness. I bought the API test kit and it gave me the same results. I've lived in places with both hard and soft water, and the water here definitely "felt" soft, so to be honest I was surprised the KH was as high as it was. I did test the KH against some 4dKH solution and it matched up. I haven't checked the GH bottle yet though...I think Hoppy has a way to calibrate it on here, I'll do that the next time I have some free time just to confirm, although I do think the results I have are at least close to true.

I have come across a few posts on the internet where someone was in the same situation as I am. It's definitely an unusual combination though. I've wondered how it comes to be...I'm assuming the water is naturally soft, but the water company is adding something to raise the KH.

Does anyone have any opinions on whether or not I'll need to dose additional potassium? It is a 40 gallon tank, and I do 50% water changes a week. So if I add 2 tablespoons of GH booster a week to get to a GH of 6, how much potassium am I adding? Would I need to add more? I know it is difficult to OD on K, but I don't want to add more than I'm taking out and end up with a dead tank in a couple months.
 

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gh and kh has nothing to do with each other, they both does not have to be equal either. for plants its always better to have low KH 5< if its higher than that some plants start to suffer, however they can tolerate higher GH.

you do not have to go crazy with gh booster, keep it around 3-4. you can aim potassium for around 25-30ppm, Ca around 25-30ppm and mg around 5-8ppm.
 

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When I suggest that the GH and KH should be roughly equal, I am answering this question:
How to remineralize RO or Rain water.

In nature fish live in water where the GH and KH are roughly equal. This means there is a certain level of minerals (Ca and Mg, tested by GH) and a certain level of carbonates (tested by KH). The carbonates are a buffer that stabilizes the pH.

So, my goal in suggesting that the GH and KH be roughly equal in an aquarium is so the fish are in the water that most closely matches the lake or river they came from.

In this case, the tap water has high KH and low to no GH.
I would suggest using GH booster to raise the GH to whatever level suits the fish, and ignore the KH. Anything from about 3 degrees (soft water fish) on up (for harder water fish). Almost all aquarium plants are fine with a much wider range of conditions, so whatever suits the fish, go for it.

Yes, adding GH booster that includes K may mean that you will not have to add other sources of K in great amounts. Depends on how much GH booster you need to add to maintain the GH you want in the tank.
 

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Discussion Starter · #11 ·
Thanks for the input everyone, and thank you for the explanation Diana. That does make sense regarding matching the water in the wild. The fish I'm keeping do like their water on the harder side, so I'll add enough GH booster to keep them happy.
 
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