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Re: [APD] Aquatic-Plants Digest, Vol 93, Issue 4

> From: Bill D <pabillpers at gmail_com>
> Subject: Re: [APD] Neglected tank
> To: aquatic-plants at actwin_com
> I think GH and KH are more important to the well being of fish than pH, GH
> more so.
> The confusion comes from the fact that pH is directly related to the KH of
> the water, and in many environments GH and KH are both "high" or "low" and
> the pH reflects that.
> It would be interesting to test this, but it's very difficult to create,
> say,  water that has a high pH and low GH/KH, or a low pH and a high GH/KH.

While a natural (or healthy!) environment with a high KH/GH and low pH is hard to imagine, waters with a high pH and LOW KH/GH can be observed on a daily basis in the wild.  In small bodies of water with large amounts of vegetation, pH swings wildly during the course of the day.  First thing in the morning, after CO2 has built up over night, it's not uncommon to find a pH of 5.  In this same body of water late in the afternoon, when the plants have been photosynthesizing, and sucking CO2 out of the water all day, these same bodies of water will often register a pH close to 8.  The fish in these habitats have absolutely no problem adjusting to these changes.  

Even many streams have daily pH fluctuations, and many of our aquarium fish adapt to the changes without difficulty as well _as long as_ adequate O2 levels are maintained.  The fish that don't adapt well to changes of pH are those that inhabit larger bodies of water and particularly fast running water.  For instance, Discus do not, typically, deal with these large fluctuations in the wild, because the volume of water is so vast, there are no plants to remove Co2 from the water during the day, and the water is also naturally acidic because of tannins in the water, with or without build-up of CO2.  So these fish tend to remain less tolerant of pH CHANGES than other aquarium fish do, though captive raised strains can usually be acclimated to a wide range of pH as long as the changes are done slowly, and then remain relatively stable.BTW, this is not a phenomenon unique to tropical waters.  You can go test it yourself in local streams/rivers vs. a local weed-choked pond.  You wi!
 ll be amazed at the pH swings AND the thriving fish life in these ponds.


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