Slow Ph Drop

[flame]

Before RO/DI PH 8.3 - 8.4
After PH Now 8.0 (Over 2 weeks and 2 water changes 1 gallon a day top off)

Ok I have noticed a slow drop in my PH since I started using the RO/DI unit. I test the water from the unit and got a PH of 7.2. Would I need to add backing soda or some other buffer to the water before I top off. I did test and found the 2 table spoons brought the PH up to 8.4. I do not think its an CO2 issue my house is not that tight and we have the windows open a lot. Any help or suggestion would be appreciated.

Thanks in advance

[Reptoreef]

A kalkwasser addition would do the job well. Baking soda will drop PH while washing soda will raise PH both will raise alkalinity, though. Kalkwasser added to make up for evaporation will help to raise PH while balancing calcium and alkalinity. I first recommend using a 2 part or turbo calcium and a reef buffer to bring your alk and calcium to desired levels of ALK... 8-10 dKH and Calc... 400-440.

[flame]

Alk is 10 and calcium is 400

[Reptoreef]

sweet!!!! Then a late pm/early am kalk addition would work perfectly. I have a reactor that doses as needed, but it can be done very successfully by drip durin those lower ph hours.