pH too High?

[spud71]

Originally posted this in the newbie section, was was told to try reposting here....

What makes pH go high in a tank? My 50 gal (+10sump) ranges from 8.33 at night to a round 8.58 during the day.

Is this too high? I am concerned that it is and I have seen it peak at 8.61

My dkH is at 10.9 and my calcium level is 480, measured this morning (salifert kits) with a pH of 8.33 and temp of 77.5 (tank is maintained with a Neptune Jr controller at 78 +- .5 )

I have two 175w Mh (10k XM) and two 96W PCs (one actinic/10k and one actinic). The PCs are on for 12 hours and the MH for 8 of those 12.

The tank is very lightly stocked right now having just cycled; 2 false percula, 1 royal gramma, 1 squamosa, 2 mushroom polyps and a reef cleaning crew of snails and hermits. All save the added cleaning crew were moved recently from a smaller tank.

Can anyone tell me what steps I can take if this pH is too high? I doubt I will be able to get a CO2 injection system though which is the only solution I have seen so far.

Other facts that might be useful, salt water mix instant ocean and ro water
50 pounds of live rock, 50 pounds of aragonite sand bed.

Thanks for any info.

[Randy Holmes-Farley]

High alkalinity and the use of limewater and high pH two part additives all contribute to overall higher pH. During the day, photosynthesis uses CO2 and drives the pH higher still.

I don't like to see the pH get much above 8.5.

How are you supplementing calcium and alkalinity?

This article may be useful:

High pH: Causes and Cures
http://reefkeeping.com/issues/2005-03/rhf/index.htm

[spud71]

I am not dosing supplements as the alkalinity seemed high enough. Actually I performed a 10% water change last night and did not see any change in the pH value, however a week ago I had 12dkH alkalinity and 300 calcium. The pH appears to be increasing since I added livestock, which I guess is not to be unexpected.

When the tank was cycling it was still reading around 8.4 during the day.

I read the page you linked, and wondered what you might suggest. It seems that my problem is not associated with adding buffer solution. Is it insufficient aeraton? I have a berlin classic protein skimmer in the sump. Is the lighting too intense?

Thanks

[Randy Holmes-Farley]

How are you measuring pH? By far the most common reason for high pH in the absence of any additives is pH measurement error, and the pH really is a bit lower.

[spud71]

I am using a Neptune Systems pH probe via their Neptune Jr controller. I have also tested using a color indicator test kit and the results seem to agree.

[Randy Holmes-Farley]

If you use a quality calibration fluid recently, then it may be fine. These articles may help:

Measuring pH with a Meter
http://www.advancedaquarist.com/issues/feb2004/chem.htm

A Comparison of pH Calibration Buffers
http://reefkeeping.com/issues/2005-02/rhf/index.htm


More aeration would probably bring the max pH down to a reasonable level.

[spud71]

Whats the easiest way to effect more aeration? Adding more powerheads to the water to create more surface area on the surface?

One question I have from reading your articles,

What do you do to adjust high alkalinity and low calcium without raising the pH? It seems that adding calcium supplements would bring up the calcium, but that would also raise pH, or did I miss something?

I admit I have always found chemistry a bit confusing

Thanks

[bertoni]

More aeration can be supplied by a skimmer, or a larger skimmer, or by more flow in the tank. If there's a surface film, pointing a couple of powerheads up a bit at the surface might help remove it, and that might help aeration as well.

A calcium supplement like calcium cholide will have no significant effect on pH. For high alkalinity, the best approach is likely to wait for it to decline on its own.

[Randy Holmes-Farley]

Do you have a skimmer now?