questions about ph & hardness

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harmony

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Feb 25, 2003
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I've read that it is possible to increase ph & alkalinity without effecting the gH of your water. But is the opposite true? Is there a way to increase hardness without also raising the ph?

Also… I was wondering… for those people who alter their ph or hardness, how do you deal with water changes? How do you keep your water conditions stable and constant? For example, I read that adding crushed coral to your filter can help buffer and raise your ph. But how much would one need to use? Is there a way to calculate this?

Thanks :)
 
Originally posted by harmony :

I've read that it is possible to increase ph & alkalinity without effecting the gH of your water.

No, the carbonate hardness or alkalinity (KH) is part of the total (German: Gesamt) hardness (GH).

But is the opposite true? Is there a way to increase hardness without also raising the ph?

Increasing the alkalinity stabilizes pH and generally raises it. You could add magnesium sulfate (Epsom salts) or calcium sulfate (gypsum) and raise the total dissolved solids without affecting the carbonate buffer. But why?

I read that adding crushed coral to your filter can help buffer and raise your ph. But how much would one need to use? Is there a way to calculate this?

Try a tablespoon per ten gallons and watch the pH and KH after a week. You may want more... The lower your pH and more acid the water, the faster the crushed coral will dissolve: it's a negative-feedback kind of thing, a buffer. That's why calculations might be tricky...
 
Re: Re: questions about ph & hardness

Originally posted by wetmanNY:

Increasing the alkalinity stabilizes pH and generally raises it. You could add magnesium sulfate (Epsom salts) or calcium sulfate (gypsum) and raise the total dissolved solids without affecting the carbonate buffer. But why?
Click to expand...

Just trying to learn more. I've noticed that the tap water in my area tends to be very soft (about 2 dH), but the PH tests at around 7.6 (straight out of the tap, before adding any conditioners).

Try a tablespoon per ten gallons and watch the pH and KH after a week. You may want more... The lower your pH and more acid the water, the faster the crushed coral will dissolve: it's a negative-feedback kind of thing, a buffer. That's why calculations might be tricky...
Click to expand...

Thanks for the info.
 
I adjust the PH after a water change - but my freshwater fish arent particularly sensitive to this. If you have the time and your tank PH is right, you should adjust your new water to similar ph to the tank before you add it in.
 
Wetman - are you sure? My understanding is that GH is the measure of bivalent cations - Mg++ and Ca++. I have known waters where the KH was higher than the GH. - ref http://www.thekrib.com/Plants/CO2/hardness-larryfrank.html

You can raise GH without raising pH or KH - at least in theory. Calcium oxide would do it. So would epsom salts, unless the sulphate acts as a buffer (chemists anywhere?)

The Seachem Malawi cichlid salts I have claim they raise GH with little or no effect on KH or pH. If they don't contain any bicarbontes, this should be the case. Certainly I don't intend to buy the buffer seperately though - examination of the literature indicates it's just glorified sodium bicarb....
 
How many did you take care of personally? I've noticed several posts where you advocate practices that can result in serious tank crashes, and am wondering how long your current tanks have been up and running successfully.
 
I learnt as much as i could by watching, and i have had at least one tropical tank continuosly for at least 8 of those years, which i setup, looked after, maintained, stocked, emptied, transported, setup again and again and never have i had a major problem.
Have never had ick or any fish disease, or had any tanks 'crash'...
Ive learnt from my father, and from reading hundreds of books, as well as using the net, and the experience from many lfs's as ive moved alot.
Like i said - different things work for different people.

At least here we can all put our advice forward and then people can make their own educated decisions from there.
 
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