PH question

[drxdragon]

my PH levels are seeming to drop dramaticly, for some odd reason. i do a 10-20% water change a week. check the ph. and add buffer as needed.. but not to exceed the dkh levels.. one morning my ph was like 7.6 or so, so over the course of 2-3 days i brought it back up to 8.4.. but to find that two days after it went back down to 7.4 .. i now have it back up to 8.4 with the dkh level at 10 or 179kH .. dunno why its doing this
any ideas?

 

[fade2black]

Could be a CO2 buildup in the room. This is common in the winter months since most houses aren't open due to the temp. In a well sealed house this can lead to an elevated CO2 level which will depress the pH in your tank. What is the pH of the water you are using in your water changes? What size is the tank?