# pH and Hardness



## redsea (Jun 29, 2013)

Hi everyone. I am always curious of people's answers on the following topic, so I figured I should post. 

I have a question about these topics. 

1. How do you know which fish will adapt to different pH, GH, and KH ranges than what they are used to?

I would love to help others stock their aquariums, but am always unsure what fish are appropriate to be housed with the other fish (for instance, Angels like soft water, Platies like hard......does this make them inappropriate tank mates?).

Thank you!


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## Diana K (Dec 20, 2007)

Some fish have been bred in captivity for so many generations that they can handle water conditions that their ancestors could not. However, returning to the wild information is a good place to start.



> (for instance, Angels like soft water, Platies like hard......does this make them inappropriate tank mates?).


Yes. Also, Platies are cool water tropicals, doing just fine at room temperature. Angels are warm water tropicals, thriving in the uppermost 70sF to low 80s. Not compatible at all.

Here is a really quick way to see if fish are compatible based on temperature and water chemistry:

Make a tic-tac-toe sort of chart. Put the labels outside the grid. Now you have 9 possible combinations of what fish like. 
Across the top put the terms: 
Soft Water- Mid range- Hard water. 
Along the side put the terms:
Cool water- Mid range- Warm water.

Now start researching fish. 
Look up the GH and the temperature preferences. ( www,fishbase.org is a good place for this) Put the fish in whatever square is where the middle of its range falls.

Platies would be mid-range or hard water, and cool temperature. 
Angels would be soft water and warm temperature.

Since they are not in the same box it is not worth going on to see if they are compatible socially, or if the same tank decor suits them.

You can add more complexity to the chart, but for a really quick check to see if further research is worth pursuing, I think the somewhat generalized info in the chart gives you that instant Yes or No.

Yes does not mean that the fish are going to make good tank mates. Just that their water preferences are close enough that more research is a good idea. After you get several fish in one square start eliminating fish with some of these questions:
~Is one fish so large it could eat the other? 
~Does one or the other species have a dietary restriction that makes them not good tank mates?
~Is one of them aggressive, territorial or pushy and the other shy?
~Does one of them prefer rocky- gravel- sand sort of set up while the other is best in driftwood- planted tank?
~Do either of them eat or tear up plants?

And of course tank size:
A schooling fish might be small, but when you put a dozen or so in a tank that is a big bioload. 
A highly active fish cannot go in a small tank, no matter what size the fish is.


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## redsea (Jun 29, 2013)

Diana K, thanks a lot for your post and PM. They were very helpful!

So, in general, it is probably best to forget if the fish can adapt or not and just go by their wild conditions, right?

Lastly, say you wanted to make your water softer with moss. Would you make the water soft before adding it to the tank, after you take water out (for a water change), or would you just permanently keep some moss in the filter and put plain old water from the tap in the tank to be softened.

Sorry for that confusing run-on sentence!  (I hope it somewhat makes sense)


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## Diana K (Dec 20, 2007)

I do both. 

1) A water change should introduce water that is closer to what you are trying to set up and run in that tank. Do not add water that still needs to be treated. The swings in mineral levels and pH are not good for the fish. 

2) The amount of peat moss that can be used in a water prep barrel (I have several garbage cans) will prep the water very fast. If you put that material in a filter, then only small amounts fit in the filter, and the change is slow. 

The 'wrong way':
Lets say you are running a soft water tank, and your tap water is somewhat hard. 
You remove some tank water, then refill with hard water. Instant shock to the fish. Then you add some media (peat moss, water softener) to the filter that takes some minerals out of the water and adds organic acids. Since the filter volume is limited, these things take time to work, and you may have to replace them frequently ($$$). Then, just as the water is getting right, you do another water change. :-(

The right way:
Prep the water ahead of time so that it is the right water chemistry for the fish you are keeping. This may involve RO water if your tap water has too many minerals, peat moss for black water fish or other things. Depends on the tank. Do as big a water change as you want, because this water matches the tank water. No problem for the fish. 
Keep in the filter a small amount of the media that you used to alter your tap water, and if the water chemistry in the tank starts to drift, that small amount of media is enough to correct it. 


How I handle soft water tanks:
A knee-hi stocking of peat moss added to a garbage can of water, circulated overnight. Include dechlor. If the house is cold I would then heat the water to bring it close to the tank temperature. 
These tanks would have peat moss in the filter. 

Hard water tanks:
Add the right minerals to make the GH and KH proper for the fish. I use Seachem Equilibrium or Barr's GH booster for GH and baking soda for KH. Include dechlor. Circulate the water for an hour or longer, until the minerals are dissolved. 
These tanks would have coral sand or oyster shell grit in the filter, and often in the substrate.

Brackish water tanks:
Add the right amount of the salt and mineral blend that is used in marine tanks, just not as much of it. Include dechlor. Circulate at least an hour, until it is well dissolved.
These tanks have coral sand substrate and oyster shell grit in the filter. 

I use fountain pumps to circulate the water. Sit the pump on the bottom of the garbage can, aimed upward. The water does not actually fountain out of the can, but does circulate vigorously in a pattern called a flume. This is the best way of making sure the water is in equilibrium with the air. I occasionally notice that the tap water holds a lot of air that is released over about half an hour when treated this way, but if I used the tap water directly in the tank I would lose fish to it.


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## redsea (Jun 29, 2013)

Is there only so much peat/crushed coral you can add until it gets to the point where it won't change your pH or hardness anymore? In other words, can you add too much peat/crushed coral? Or will it, after a certain amount, just stop lowering or increasing the pH and hardness?

Thanks a lot, your response was fantastic!


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## Diana K (Dec 20, 2007)

Yes, there are limits to how much change in pH and mineral content you can expect from crushed coral and related materials. 

When the water is more acidic, more of the material dissolves. As it dissolves the water gets harder, higher pH so the material does not dissolve quite so well. 

Coral sand does not dissolve any more once the tank is pretty good for most rift lake fish, many live bearers, and (of course) does not dissolve in marine tanks unless the pH etc gets lower. 

My Lake Tang tanks and live bearer tanks are all pretty much at pH just under 8, and GH and KH in the low teens (degrees). 

For more about this sort of reaction look into Equilibrium (a chemical concept, not the Seachem product). That means a chemical reaction that just goes so far. When something happens to push it one way or the other it tends to shift back to where it was, up to a certain point. 


Similarly with peat moss. The reaction is a bit more complex, though, and the peat moss wears out so quits reacting after a while. However, using fresh peat moss I can get the pH down to the low 6s, and when I combine this with a substrate that removes KH the pH will go off the scale low, into the mid 5s, I think. 
And this is starting with tap water with a pH that is raised by the water company with sodium hydroxide to the upper 7s. 
If you want to see what your local peat moss can do set up a bucket of water with some peat moss (a cup to 2 for a 5 gallon bucket) and monitor the pH, GH and KH. Some peat moss acts similar to an ion exchange water softener and will remove positive ions (Ca and Mg, for example) and add H+ into the water. So the GH will go down, too. The peat moss I am using does not seem to do that very much.


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