Chronic low pH

[Rusalka]

I use to be able to maintain a stable pH BUT, for the last month and a half, it has been running in the 7.6/7.7 range. I have been dosing Kalk like crazy to try and keep the pH up to at least 8.0, but as soon as i stop dosing, right back down to 7.7 range. At the present time, i have a 5 gallon jug with saturated limewater that i am dosing at the rate of 300 mls/hour directly into the sump.

My Cal has also dropped, then again i had a "snow" event before Xmas that turned my tank white and i have not been able to get it above 200 since then. Alk runs between 3 ~ 5.

Last nite i made some changes.

Prior setup: CO2 reactor output went into a jug of Kalk that was plumbed into the inlet of my Bullet One protein skimmer. (note: pH problem was prior to the addition of the CO2 reactor. It was added to help with Alk/Cal problem.) Also, CO2 is turned off at nite. CO2 water inlet comes from tank return line from sump.

Now i just have the output of the CO2 reactor going directly into the sump and i slowed the flow rate way down.

Guys in my club are at a lost for what is causing the problem. I keep reading that it is high CO2 in the tank water. I have tried adding air stones to the sump for airation, did not work. I did not think it would considering my protein skimmer setup. pH problem started befor the addition of CO2 reactor.

My wife is getting mad at me because i "tinker" with the tank every nite (monitoring pH & ALK/Cal levels).

HELP

[Randy Holmes-Farley]

I have been dosing Kalk like crazy to try and keep the pH up to at least 8.0, but as soon as i stop dosing, right back down to 7.7 range.

That is normal. The pH is being lowered by excess carbon dioxide, and when the limewater is stopped, the excess CO2 dominates. It is needed permanently. It is not a one time correction.

You might check the calibration of your pH meter to make sure the pH has shifted down, and it is not a calibration problem.

My Cal has also dropped, then again i had a "snow" event before Xmas that turned my tank white and i have not been able to get it above 200 since then. Alk runs between 3 ~ 5.

Use calcium chloride to raise the calcium that much. Limewater cannot accomplish that task.

Guys in my club are at a lost for what is causing the problem. I keep reading that it is high CO2 in the tank water. I have tried adding air stones to the sump for airation, did not work. I did not think it would considering my protein skimmer setup. pH problem started befor the addition of CO2 reactor.

That part is easy. It is excess CO2. Whether it is from your air or just your tank water is what needs to be determined via the aeration test described in this article:

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

this article will help with the calcium chloride addition:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm