crazy pH swing?

[swomley93]

Hello, I have had my 55 gallon setup for over a year and it's very established, recently my catfish regurgitated food and caused a mini cycle so..I changed half the water let it settle and everything was fine, I have been carrying a 7.8 pH the entire time, but now all of a sudden a week after the mini cycle it's 6.8 I have live plants growing in the filter as well but using no fertilizers or anything at all just plain dirt and gravel with no way for the dirt to enter the aquarium could anyone explain this

 

[joe jaskot]

As an aquarium ages, the water becomes more acidic and the pH drops. Best thing to do is to add some crushed coral to the tank or add some baking soda while doing a water change.
Did you check the pH of your source water?

 

[swomley93]

I did not but it hasn't changed forever I couldn't see it randomly changing overnight ya know?

 

[HarleyK]

What's your water hardness?
gH and KH?

Hardness stabilizes pH

 

[swomley93]

I don't know the gh and kh but I know it's very hard water

 

[jwh]

Check your nitrate levels, when last did you clean your filter, and gravel, decomposition of bio material will drop the pH of your water