Why is my pH dropping during the day?

[jamesbuf]

Isn't your pH supposed to increase when the lights are on? I top-off through my kalk reactor only at night, which keeps my pH between 8.1-8.25 during the night. But the last week or so I've noticed my pH dropping during the day. It was 8.2 when I woke up and its dropped all the way down to 7.85 right now. I re calibrated my pH probe 2-3 days ago thinking that may be the problem.

 

Ideas?

[wreck]

Is your ALK low? Magnesium? Are you using a calcium reactor with too much CO2? If all that is ok maybe just start dosing some Kalk during the day too.

Wreck

[ctenophore]

What's your alkalinity? If it's in normal range, you probably have a bad probe or calibration error. It could be that your pH at night is really around 8.5-8.6 due to the kalk, then falling in the day to a "normal" 8.1-8.2.

[SteveM]

James,

I had been experiencing a similar problem and it turned out that my PH probe was going bad. Even though I was able to calibrate it correctly for a while, it eventually had to be replaced. Now that I have a new probe on my PH has been reading in the 8.3 range during the same time it had been showing 7.9-8.0 with the old probe. I would suggest checking your PH with something else to see if your PH is actually ok or really dropping.

[jamesbuf]

My alk and calcium are within normal ranges. I haven't started using my Ca reactor yet. Its on my list to turn on this week. Just using a Kalk reactor right now.

 

I'll switch out the probe with another one I have. The probe is a "lab grade" purchased in the last large ACIII groupbuy. The one that Bob ran. Its only been running for maybe 6 months. I'm going to be pisssed off if this is what's wrong. Have to wait till tomorrow though. I've got my "pre-boards" tomorrow at 8am. I'll check back in tomorrow, if I'm not to drunk to type

[YBeNormal]

The probe is a "lab grade" purchased in the last large ACIII groupbuy. The one that Bob ran. Its only been running for maybe 6 months. I'm going to be pisssed off if this is what's wrong.

 

Oh sure, blame it on me!

[jamesbuf]

Well the good news is that I passed my pre-boards today.

 

Bad news is that I hooked up the second pH probe I got just about the same readings. The new probe is reading .05 -.08 points higher than the other. I recalibrated both of them too. My pH was between 7.80-7.95 during the day. Its rising now since my topoff is starting to run. Still confused at this point.

 

I rechecked my ALK and its at 5.5meq/L. This is pretty high isn't it? I tested it twice using the "higher accuracy" mode with my kit. 22 drops of solution to get the blue to turn to light green/yellow. 22/4 = 5.5 meq/L. I'm using the Instant Ocean ALK test kit I got from BRK. Johnny said he and Copps tested this one against other much more expensive kits and it help up with them.

My Calcium is ~480.

Nitrates in main tank is ~10.

Nitrates from sulfer denitrator is zero.

Don't have a Mag test kit.

 

All I'm dosing is Kalk through a Kalk reactor. I'm starting to worry now because the polyps on my corals haven't been fully extended for around a week now.

[Highland Reefer]

My pH readings have been similar to yours over the past week. The only thing I can attribute it to, is that I have had a lot of CO2 producing visitors in the house this past week and have had to keep the windows closed off & on do to the rain. I opened the windows today and now my pH levels are back to normal. I find that my pH fluctuates similar to yours on a regular basis, depending on whether my windows are open or not. I also find that when it is raining outside and my windows are open, that the pH levels drop.

 

If your pH ranges are between 7.8 - 8.4, then these are acceptable levels, as long as the swing is not to drastic. After talking to Copps at the last meeting, I am not worried as long as my pH is between these levels. Copps was more concerned about keeping the alk levels stabilized. He had recommended that I keep the alk. levels at the high end of the normal range. The normal range is 2.5 - 4 meq./L. I am starting to get tired of opening and closing windows to keep my pH up to 8.2 -8.4.

 

I would be more concerned about the alk. level being up so high and would properly stop adding kalk until your level drops down below 4 meq/L. After you reach the proper level, than you want to adjust your calcium reactor to maintain the proper alk. levels and forget about the pH. Measure your magnesium and make sure the levels are in the correct range. Supplement your calcium levels if they are to low at the proper alk. In other words, your calcium reactor should be used to maintain your alkalinity and not your calcium.

 

This is a helpful article by Anthony Calfo entitled: "Alkalinity for Marine Systems":

 

http://www.wetwebmedia.com/alkalinity.htm

 

My two cents.

 

Congrats on passing your boards.

Edited May 15, 2008 by Highland Reefer