Have had consistently low pH in my three tanks over the past few months. Finally found the Reef Chemistry Articles pages and bought Ca and Alk kits to go along with our Pinpoint pH probe and Hanna Instrument monitor to get to the bottom of the problem.
The tank I am currently working to get balanced is a 42 hex with 50 lbs LR, 3" aragonite sandbed, soft/lps/sps corals, five small fish, Hagen 802 powerhead with Quickfilter attachment filled with foam for nutrient export. Weekly tank maintenance consists of cleaning glass, basting the tank so the foam can pick up and export crud, 15% water change, remove, breakdown and clean all parts of the Hagen PH (in tapwater) and the foam media (in changewater). Use RO water exclusively in all tanks for NSW and top up.
Alk 2.50 meq/L
Ca 420
Before lights on pH 7.70
Before lights out pH 8.06
Ammonia/nitrite/nitrate 0 ppm
Also did a 1/2 hour test of NSW aerated with an air pump, both inside and outside the condo this morning:
Inside begin pH 8.07
Inside end pH 8.07
Outside begin pH 8.07
Outside end pH 8.31
So we've got three things going on in this tank:
- slightly low Ca
- very low Alk
- very low pH
To slowly bring up Alk, I added one tsp of baking soda mixed in RO water to the 42g this morning. pH dropped from 7.89 to 7.78, which surprised me because I thought pH would rise
For the past 4 days, have also been using HBH Balance blocks as a means of increasing calcium and raising pH. pH has not increased, but has rather slightly decreased by .1.
Living in Edmonton is dang cold in the winter. Current outdoor day/night temps are -11/18 C. Our condo is new and retains heat very well, indicating it is more or less a sealed box. To compound the problem, we have in-floor heating so there is no air coming in from outside unless we specifically open the patio door a few times a day to cool off the place and exchange CO2 for O2.
Here are my questions:
- when adding calcium and baking soda to increase calcium and alk, respectively, shouldn't I be seeing an increase in pH?
- if pH should be rising and is not, is the CO2 in the condo depressing pH when it should be rising?
- how the heck are we going to get rid of the CO2 in our condo when it is so freaking cold outside? I don't mind opening the patio door for 10 minutes a few times a day, which does refresh the air, but that's not been enough to keep O2 levels even near optimum levels. Any ideas about a heat exchange system that might help increase O2 and decrease CO2?
TIA for your time and consideration.