Low PH in the winter.

[Zacco]

If your struggling to keep your PH levels above 8.0 in the winter, it's probably due to the fact that you do have enough Oxygen in your house in the winter months and Carbon Dioxide levels are elevated due to the fact of lack of fresh air. Newer houses these days are so air tight, there is no way to get fresh air in the house short of opening all the windows and doors in the house to swap air. Also furnaces use a lot of oxygen when burner's are lit. I have a 1/2 inch line run directly outside that supply's fresh oxygen rich air to my skimmer to alleviate this problem. Make sure to break surface tension in your tank or sump to get oxygen in your tank too.

 

[Zacco]

Correction. ( do NOT have enough oxygen in your house)

 

[mike007]

This is very true. When the weather allows open up some windows and air out your house.