Ph Help Please

[imat]

OK, so i have had my tank since September.  I bought it of craigslist and it was already running with fish and had been for years.  It is a 55 gallon tank. Levels in our tank have been great until recently. My ph went from being 7.0 to 7.6!!!!
I can tell my fish are not happy. My otos won't do anything.  I havn't added anything new to my decorations.
I just tested my tap water and it is coming out 7.6
Is it normal for tapwater to change so much in PH? I am not exactly sure what to do to lower my ph level back to where it was without using chemicals. I know driftwood is supposed to help, but how much does it help? Does it continuously help or will my PH still be an issue later?

HELP!!!!!

 

[LyraGuppi]

Did you add anything new to the tank?

 

[gmc1]

try retesting your water again.I had same prob last week.the results were through the roof.someone suggested a good shake and retest and it was ok.someone with more experience will be along shortly I'm sure.

 

[LyraGuppi]

Oh, derp-a-lerp, nevermind on the first post, didn't see that part.

 
+1 on GMC's post.

 

[Akasha72]

it's perfectly normal here in the U.K for tap water Ph level to fluctuate. They often fluctuate after a lot of rain (or snow melt) and they can fluctuate around the time the water companies do a clean of the system.
 
Obviously I can't speak for America though but I can't see how it would be any different. 
 
Someone is probably going to jump all over me for saying this but there would also be Ph fluctuations in the wild and so I doubt the fish will notice

 

[TwoTankAmin]

Even before dealing with treatment options used by water companies, the first place to look is always at levels of dissolved CO2 in water. Co2 levels affect pH levels.
 
When water comes out of the tap one of three possibilities exist regarding the level of dissolved co2 in the water:
 
1. The water contains and equilibrium level of co2 with that of the normal atmospheric exchange levels. That is the water is in balance and no Co2 exchange is immediately need for it to be in that balance.
2. The water contains too little co2 relative to its normal equilibrium level. This would tend to cause the pH to be higher than normal for that water.
3.The water contains more co2 relative to its normal equilibrium level. This would tend to cause the pH to be lower than normal for that water.
 
Over a bit of time, any imbalance, as in 2. or 3. above will due to surface aggitation or being allowed to sit for a day or so. But surface aggitation promotes gas exchange. So we can test directly from the tap and get one pH reading and then test again after the water has reached equilibrium levels and get an entirely different number.
 
Therefore, to prevent any bias due to levels of dissolved co2 in out tap water, we need to insure that the co2 levels for that tap water are "normal" before we test it. We can do this in one of 3 ways:
 
1. Put the water into a clean container with a lid and shake heck out of it. It is important to have more air space than water space in the container.
2. Put the water into a clean container and drop in an airstone for an hour or so.
3.  Put the water into a clean container and let it sit out overnight.
 
What all three methods are doing is allowing the equilibrium level for co2 (and other dissolved gasses) to be reached. This is the true pH level of out taps and the number we need to know.
 
More co2 in the water makes it more acid and less co2 makes it more alkaline. Acid water is more damaging to supply systems, so many water companies artificially raise pH levels during treatment and transmission to minimize the potential for such damage.