Spike in PH balance

Question
I currently have a 10 gallon take that continually spikes low.  I change the water every weekend and the filter every other week end.  After water changes, the PH balance is 7.0 but after an hour it becomes lower and lower.  In the morning it reads 6.0.  I do not have any type of wood in the tank although I do have several plants an air one bubble wand and a small salt rock to try and maintain PH level.  Need help.

Answer
Hi Patti
The water change is good, once a week.  Not sure how much you're changing, but usually 25% is good(as long as it's not overstocked).  You shouldn't have to change the filter that often though.  A lot of your beneficial bacteria is living in there, as well as other parts of the tank.  What kind of filter is it?  If it's a regular hob(hang on the back), with the filter pads, every few weeks just rinse it out in a bucket of the dirty tank water.  Just scrub it with your hand and reuse it.  Only need to change those out about once every 3 months.  

For the ph, are you using tap water or another source?  Try testing your water that you're using(assuming it's out of the tap), pour a glass of water test it.  Leave it out for a few hours, then test again.  Is it changing dramatically like in your tank?
Now, plants will cause ph fluctuations as well, though I can't say for sure how much.  They'll pull the carbon dioxide out of the water to do their photo synthesis thing, then at night they won't-because there's no light.  So it'll build up again.  

What kind of salt rock is it you added?  Was this happening before you added that(I"m guessing it was since that's why you added it, but have to ask).

And you're not using any of the ph up/down chemicals correct?


Christy