Low Ca/Alk/pH in Tank, High CO2 in Condo

[Beverly]

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.

[Samw]

I'm struggling with high CO2 and low PH as well in the morning. The tank is in my bedroom and when I close the door while I sleep, the PH the next day is about 7.5. If I leave the door open, the PH is about 7.7. Both still too low but obviously lower when the door is closed. One way to fix my problem is to have reverse photoperiod set up on a refugium. But since I'm not going to set up a refugium, that won't fix my problem. Is that an option for you?

[Beverly]

Sam,

No, that's not an option for three tanks, and all tanks suffer from low pH because of the excess CO2 in the house. I even feel kind of sluggish after a night's sleep, so the CO2 is not only affecting the tanks.

What we set up tonight to try to decrease CO2 and increase O2 overall, is open the two bedroom windows a bit, one facing east, the other south. Then we pulled an ocellating fan out of storage and set it up outside both bedrooms with the air being pushed into the living/dining areas where the tanks are. Am going to experiment with this for awhile, while it is still relatively warm

DH is going to ask the building maintenance people at work (in one of the Telus Towers) what they might suggest. Will report any positive results.

[mnoll406]

Hey Bev,
Have always experienced lower pH on most of my tanks, and my Ca, and alk are a little low. Bought the coral propagation book by Calfo, and he recommends; For water change: aerateing for a day, add buffer, then mix salt mix.
For top off: Aerate water then add buffer.

Just started trying so I will let you know the outcome. It won't help with the CO2 probs, but Calfo says the ro/di water ends up using up the buffer in salt mix, or your system, and that's why you have Ca and alk problems. Kinda makes sense to me. I used to work in a lab, and RO/DI water always had low pH. Hope this helps.

Mike

[Beverly]

Well, had the windows open last night and added an ocellating fan in the hallway between the two rooms pointing into the dining/living rooms where the tanks and NSW storage area are. Interesting results

Yesterday's pH with 1/2 hour aeration:

before aeration pH 8.07
after aeration pH 8.07

Today's pH with 1/2 hour aeration:

before aeration pH 8.15
after aeration pH 8.22

Both water samples were from the same pail, covered with a lid, that had been aerated with a powerhead for the past 4-5 days.

I do believe the CO2 was replaced with O2 overnight with the windows open and fan going and the NSW in the pails even benefitted from the extra O2. It even smells fresher in here What we're going to do when the temps dip to -30, I don't know, but for now the open window thing is going to be a must.

Now, all I have to do is increase alk and I'll be feeling good

[Samw]

Hi Beverly. Have you continued your use of Balance Blocks? Have they improved anything in your tank?

[Bob I]

Here's a thought. Stop measuring, and all the problems will miraculously disappear. Be like me go the minimalist way, and be happy. Stop measuring and worrying, and be happy. You will be more than a little amazed how well things will go.

[Scavenger]

Originally Posted by Beverly

- when adding calcium and baking soda to increase calcium and alk, respectively, shouldn't I be seeing an increase in pH?

I have read that baking soda will briefly reduce the ph before it raises it. Maybe someone with more experience could verify this.

[StirCrazy]

sorry misread the post.

out of curiosity have you measured your PH 2 days after you do all your cleaning. and 425 isn't low ca, it is actualy higher than NSW levels.

Steve

[Samw]

Originally Posted by StirCrazy

Im with Bob, sorry to say but you are worring about a 0.15 swing in PH.. most tanks swing more than that in 6 hours I think if you just measure your PH once a week you will be taking enuf info to know whats going on. unless you have regular PH crashes

Steve

Steve, are you referring to me or Beverly? Both of our tanks are swinging more than .15. Beverly's was swinging from 7.7 to 8.06. My PH was swinging from 7.5 to 8.4.