I just don't understand pH...

[RyanH]

Randy,

I have a 55g tank with 20g sump, no skimmer, and the tank is on an outside patio. The tank has an open top, and the sump is open as well. I drip limewater at night to keep the pH up. It would go down to the 7.8-7.9 range without dripping limewater. In the mornings, the pH (Pinpoint monitor) is about 8.2.

First thing in the morning, I add B-Ionic (the higher pH variety), and the pH goes up to about 8.35. By the time the sun sets, the pH will go as high as 8.6. I have been pouring small quantities of vinegar in the sump to control the high pH.

My alk is about 10 dKH and calcium is about 400.

I guess I should get the lower pH B-Ionic, but i still have issues with high pH. What gives?

Also, what is the effect of baking soda on pH?

Thanks.

Ryan

[Boomer]

Do you have allot of algae in the tank. They can-run up the pH as the pick-up CO2 and use some of the HCO3.

[RyanH]

i have a bunch of chaetomorpha in the sump. only coralline algae in the main tank.

[Randy Holmes-Farley]

It sounds to me like the tank may not have enough aeration. In that case, CO2 builds up at night, lowering pH, and the tank gets depleted in CO2 during the day, raising pH. Maybe drop an airstone in the sump.

One suggestion is to use a low pH two part additive system, like my DIY using baking soda, or B-ionic Bicarbonate. Vinegar in the limewater is another resonable measure to limit the rise.

Baking soda will have a small initial pH lowering effect.