Changing GH and KH - The Planted Tank Forum
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post #1 of 8 (permalink) Old 01-14-2013, 03:23 PM Thread Starter
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Location: Michigan
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Changing GH and KH

Hello all, I don't know exactly where my hardness was need to he but I have a good idea and I'm way off in regards to both types. I checked my tap my soon to be planted and my Malawi cichlid tank here's what I got

Tap: 10DGH / 4DKH
Planted: 10DGH / 2DKH
Malawi: 10DGH / 1DKH

So in my planted and Malawi I need more KH to keep my PH stable right? And since they are rift lake cichlids I'd like to see it at or above 12DKH. And more specifically for my planted I need a lower GH correct? At least down to like 7DGH for the health if the plants? How can I accomplish this? I've been told already that adding 3 tsp of baking soda per 50 gallons of water will raise alkalinity 1 degree. Is this a good equation? And to lower GH I was told to cut my water with RO water. But I'm just asking around to make sure I do the right thing and not the wrong thing.
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post #2 of 8 (permalink) Old 01-14-2013, 03:38 PM
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Hi Colorblizzle,

I don't do African rift cichlids so I will let others comment on that.

I follow Tom Barr's suggestion that he made when he visited GSAS a couple of years ago. I asked him about his recommendation FOR water hardness and he said he targets about 5.0 dGH and doesn't worry about dKH as long as there is no danger of PH crash. We have very soft water here in Seattle. I use Seachem Equilibrium for raising the dGH to Tom's recommendation and if necessary add enough NaHCo3 (baking soda/bicarbonate of soda/sodium bicarbonate) to keep my dKH at about 2.0. My plants seem to do well at these levels and no PH problems.

I use the Seachem calculator to determine how much Equilibrium to add to raise my dGH and this calculator to determine how much NaHCO3 to add to raise my dKH.

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Last edited by Seattle_Aquarist; 01-14-2013 at 04:51 PM. Reason: add calculator links
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post #3 of 8 (permalink) Old 01-14-2013, 03:45 PM Thread Starter
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Thanks for the link to the calculator. As far as the KH is 2 enough to stabilize the PH? And is that good enough for most South American fish?
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post #4 of 8 (permalink) Old 01-15-2013, 01:59 AM
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Yes, KH of just a couple of degrees is fine for soft water fish and plants. It is enough to keep the pH stable, as long as other things are stable. You could raise it a bit if you want.
GH of 10 is fairly high for soft water fish, and probably at the low end of OK for the Rift Lake fish.

My Lake Tanganyikan tank definitely needs some help.
Tap water GH and KH are pretty close to 4-5 degrees most of the time.
I use baking soda to raise the KH.
1 teaspoon of baking soda per 30 gallons will raise the KH by 2 German degrees of hardness.
I use Barr's GH booster or Seachem Equilibrium for GH.
Instructions are on the label.
I also have coral sand substrate, and add oyster shell grit to the filter.

On water change day I will prep the water ahead of time in a garbage can, adding enough baking soda and GH booster to make it match the lake.
Then, through the week, as the plants, fish and microorganisms use some of the minerals, the coral sand and the oyster shell grit stabilize the mineral levels. Stays really stable that way.
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post #5 of 8 (permalink) Old 01-15-2013, 02:06 AM Thread Starter
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Well I've been doing alot of research and have decided to leave the GH alone in both tanks I may put some RObwater in my planted to drop it to about 8. But in gonna leave it alone for my cichlid tank. As far as the alkalinity goes ice started dosing baking soda today to see what it does. Just a little at a time. I also understand I'm gonna have to dose the new water prior to water changes. I'm hoping for an alkalinity of 5 for my planted and 12 for my Africans. All of the fish at my local fish store are accustomed to this water except a few species. I plan on keeping either guppies danios or small tetras in my planted as well as shrimp and otocinclus
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post #6 of 8 (permalink) Old 01-15-2013, 02:16 AM
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Guppies are fine in hard water. The best Gups I ever had were in my brackish water tank.

Danios are pretty adaptable.
Most Tetras' ancestors are soft water fish, but if they have been raised in captivity they are OK in harder water.
Otos are often wild caught and are probably the least adaptable of the livestock you list.
Research the shrimp. I know there are different requirements for the different species, and you will probably have the best luck if you find the right species for your water.
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post #7 of 8 (permalink) Old 01-15-2013, 02:22 AM Thread Starter
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Hmmm the recipe I found told me to add 1tsp per 5 gallons to raise my KH from 1 to 12 so I'm adding 1 tsp a day till I get where I wanna be also it will raise my PH significantly won't it? My PH is 7.8 right now. For my planted I really want to use celestial pearl danios
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post #8 of 8 (permalink) Old 01-15-2013, 02:06 PM Thread Starter
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UPDATE: well I found out today that I was totally misreading my results which caused me to dies wrong lol. Thankfully there's no fish or plants in my 10g yet. I thought when the vile turns blue the test is done...the drops are yellow but turn blue as soon as they hit water (that's why I was getting readings if 1-2DKH) but I found the instructions and the test is complete when it turns back yellow. So now in my tanks I have a DKH of 8 in my Malawi tank and 13 in my 10g. Ill be doing a 80% water change in that tank and start over. I added more baking soda to my Malawi tank I still want to get it to 12+ but my 10g I only want at like 5 lol
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