# Help! high KH and pH, very low GH



## pinktoes1218 (Mar 29, 2015)

I have been lurking for some time greedily soaking up the wealth of knowledge this site contains. I have read a lot about GH, KH, and pH but still need help!

My 80 gallon tank has been fully cycled for 2 weeks and currently has a bunch of plants and some fish in it. Substrate is gravel from Petco, the natural looking river rock one. Decorations are driftwood and a couple natural stones the local fish store said would be suitable for freshwater. I have been concerned about my pH which is consistently at 8.2. After trying peat and adding a bunch of driftwood all I have is a tea colored aquarium. I got the GH and KH test kit and discovered the following:

Tank: 
PH 8.2
GH 1
KH 18

Softened water:
PH 7.2
GH 1
KH 20

Well:
PH 7.2
GH 27
KH 22

I have been able to get the kh down to 14 by using RO water for water changes. 
Why is my pH higher than the water source? Could one of the natural stones be the culprit?
Is a GH of 1 too low?
Should I use a mix of well water or soft water and RO water to maintain nutrients? Should I be using any chemicals?
Any advice would be appreciated!


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## Diana (Jan 14, 2010)

pH is not a stand alone value. It is controlled by the other things in the water. 

KH is the major buffer of pH in aquariums. When the KH is high (in natural waters or in tanks) then the pH tends to be high, and not easily changed, as your test with peat and driftwood shows. 

When water is in the ground it can come in contact with supplies of CO2. It may become super saturated with CO2, so come out of the well with a low pH. 
On standing, or getting circulated in the aquarium, this excess CO2 leaves the water, and the pH rises to the more normal level when the KH is so high. 

If you want to keep soft water fish that really demand soft water, then you will have to blend a lot more RO with your tap water. You may end up with a blend that is at most 20% tap water (GH and KH would end up around 4-5 degrees), and might be as little as 10% (GH and KH about 2-3 degrees). 
Adjusting GH and KH is pretty much straight math: You want half the level, then blend your tap + RO in a ratio of 50/50. You want 1/4 of the hardness, then use 1/4 tap + 3/4 RO. 

If you are using a sodium exchange water softener, then running this water through the RO then the membrane will last longer. So I would continue doing this. The RO water you produce will have very close to no minerals, so the GH and KH will test 0 to 1 degree. 

Then blend back just enough straight well water until the GH suits your fish. The KH ought to be pretty close to the right level, and it will stabilize the pH pretty close to the right range. 
With the recipe you develop and given that the GH and KH in the well are similar, the KH ought to be about the same as the GH. If the KH is too low you could add some potassium bicarbonate to boost it just a bit. It does not have to be equal to the GH, but does need to hold the pH in the right range. 

Then, if you are keeping black water fish, you can filter the water through peat moss to get the organic acids these fish need. With a very low KH this will drop the pH some more. 

Do not use the softened water for the tank. Plants and fish need the minerals that we test as GH (Calcium and magnesium) and neither RO nor softened water has enough. GH of 1 is not enough. 

recap:
Set the GH to suit the fish. Blend RO + well water to make this right. 
Check that the KH is similar to the GH. 
If the pH is too low, you can add a bit of carbonates to raise it. 
If you are keeping black water fish, add peat moss to the prep. 

If you are incorporating this water with an existing tank, already running with fish, then do not make the change over too fast. Do smaller water changes with this really soft water, or make some intermediate recipes while the fish adjust to the softer water. 
It may take a month to get the tank water really soft, and the fish acclimated. Let it take time! 

When you buy new fish set up a quarantine tank and test the water in the bag. Make the water in the Q-tank match the bag water for GH, KH, TDS. pH is lower down. If the first three are right, then the pH will probably be somewhere about right. The others are more important than the pH.


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## BBradbury (Nov 8, 2010)

*Tap Water Chemistry*

Hello pink...

If you're not keeping and breeding rare fish species, then you can ignore the chemistry of the tap water. It's not important to the health of the tank. All you need to do is work up to the point where you're removing and replacing half the tank water every week. This alone will maintain a stable water chemistry and this is more important than trying to maintain a particular water chemistry. Trying to change your tap water and maintaining the change will create water problems for your fish and plants.

But, you're the keeper of the water. Do what you feel is best.

B


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## Linwood (Jun 19, 2014)

Diana said:


> Do not use the softened water for the tank. Plants and fish need the minerals that we test as GH (Calcium and magnesium) and neither RO nor softened water has enough. GH of 1 is not enough.


+1

In case you are not familiar with how a water softener works... 

"Soft" water from a water softener is misleading, as people think a water softener takes out "hardness". What it actually does is replace some dissolved solid (calcium and magnesium generally, which is what is "general hardness") with another (often but not always sodium). Depending on the process it usually adds two sodium for each calcium removed, so in a sense it can almost double the amount of "stuff" in the water. 

An RODI system on the other hand actually removes things (pretty much everything). 

Water softeners using sodium chloride (regular salt) are the worst to use with aquariums, those using potassium chloride are still not good, but are better, as high potassium in water usually does less harm. 

Both should be avoided. Usually outside faucets or a bypass feed is available somewhere even with "whole house" systems.


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## pinktoes1218 (Mar 29, 2015)

Thank you everybody. I am understanding this more and everybody has been very helpful.


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