# How important is pH?



## alphaparrot (Nov 28, 2017)

My 20g is almost cycled, so I'm researching fish. I've noticed that a lot of the standard beginner fish (various danios, rasboras, tetras, etc) have wide pH ranges they're comfortable in, but typically only up to 7.5 (with some only up to 7.0). I know that stability of pH tends to matter more than the pH itself, but I assume this is true _within the fish's comfort zone_.

My tank's pH has consistently measured in at about 7.6 (using Toronto tap water). If I want to get some pretty schooling beginner fish (i.e. kyathit danios, harlequin rasboras, etc), how important is it that the pH not go above their comfort range? I also notice that different sites report different pH limits, which could either be interpreted as the limit not mattering that much, or as anything near the limit being meh, regardless of the exact limit. Should I endeavor to lower my pH (maybe by adding an air pump?) if I want these fish, or will they be perfectly happy in 7.6 if I acclimate them slowly after bringing them home?


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## BillD (Jun 5, 2006)

For the most part, pH is of little consequence, in my opinion. The thing that usually causes problems with so called pH shock isn't the pH but rather differences in TDS, total dissolved solids. In general terms acidy water tends to be soft, alkaline water tends to be harder. Sudden changes in the TDS can cause osmotic shock, which many believe is the real culprit, when pH shock is blamed.
So, you can question why this isn't a problem in nature when torrential rains raise water level by three or four times their normal levels. It happens in areas of Costa Rica several times a year, and the fish survive. You would think the sudden large change in both pH and TDS would have a detrimental effect. The fish seem to survive. From this, one might surmise that the fish in these are more adaptable than some. Regardless, in an aquarium, you need to use the water available to you. You can use it as is or you can play water chemist. Most of us use it as is, and the water from Lake Ontario is suitable for most species we keep, as is, because it isn't particularly hard, while still having some buffering capabilities. 
The other consideration is that most of the fish we buy are tank bred, and often come from water much different than their native waters.Many of the "soft water" fish we keep, readily breed in tap water. That tells me they are thriving.


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## solarz (Aug 31, 2010)

alphaparrot said:


> My 20g is almost cycled, so I'm researching fish. I've noticed that a lot of the standard beginner fish (various danios, rasboras, tetras, etc) have wide pH ranges they're comfortable in, but typically only up to 7.5 (with some only up to 7.0). I know that stability of pH tends to matter more than the pH itself, but I assume this is true _within the fish's comfort zone_.
> 
> My tank's pH has consistently measured in at about 7.6 (using Toronto tap water). If I want to get some pretty schooling beginner fish (i.e. kyathit danios, harlequin rasboras, etc), how important is it that the pH not go above their comfort range? I also notice that different sites report different pH limits, which could either be interpreted as the limit not mattering that much, or as anything near the limit being meh, regardless of the exact limit. Should I endeavor to lower my pH (maybe by adding an air pump?) if I want these fish, or will they be perfectly happy in 7.6 if I acclimate them slowly after bringing them home?


I agree with BillD, pH is of little consequence.

There's a lot of misinformation out there, IMO. When I first got interested in Cardinal Tetras, I agonized over pH as well. Turned out I needn't have bothered. The cardinals did just fine over 2-3 years in my pH 8 tank water.

PH is just an indicator, and an unreliable one at that. Most "pH-sensitive" fish are actually just sensitive to the hardness of the water. For example, CO2 will reduce the PH of water without affecting its hardness. The PH swing does not affect fish at all.


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## alphaparrot (Nov 28, 2017)

Got it, thanks! That makes sense, and it's a relief to hear I don't need to play with my water's pH for standard beginner fish.


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