Board search didn't help, pH question

[kevin01]

My reef tank, although coral uninhabited, has been running for over a year now and I am working out the final wrinkles before introducing. This excerpt is from this morning's log:
1-10-02 10:00AM
Tank observed healty.
All inhabitants accounted for and acting normally.
pH noticed to be very high and Ca still too low.
Temp - 80
pH - 8.47
Alk - 7 meq
Nitrates - 0
Nitrites - 0
Ammonia - 0
SG - 1.024
Ca - 345 ppm
Po - 2 ppm
End Log
This evening when I checked the pH was 8.59 pH measurements are checked with a digital meter, calibrated just before today's morning check. I am dosing Kalk, drip method, Reef Calcium by SeaChem, twice a week, and Reef Plus by SeaChem, to load vitamins for future corals, twice a week. I feed flake in the mornings, all consumed, and brine in the evenings for the Cardinal, most all consumed. Ocasionally I feed the paper kelp or frozen dwarf angel food for the FLame. RO/DI water was just measured at 7.98. I have not seen any "snow" in the tank.
My questions are as such: Why is the pH so high? Am I over oxygenating the tank with surface action causing the pH to rise? Should I cut back on the Kalk to cut down the pH and if so how do I increase my Ca? Is this pH ok and just a product of a low bioload aquarium? I have been using this regiment for a little over a month and I still haven't seen a significant rise in Ca, only about 20-30 ppm, what is the hold up? Lastly, should I do some water changes to bring the pH down or is there something else I should do?
Sorry for all of the questions and the long history but I feel that all this is connected somehow and most of the questions relate to one centralized answer. I also tried to answer as many of the questions I thought you all would ask as I could.

 

[broomer5]

Assuming your pH probe and instrument are accurate, and your getting good results from your test kits, I would say that both your pH and alkalinity are too high.
Alkalinity of 7 meq/l = 19.6 dKH
There is much debate regarding the "proper" alkalinity level to keep, but many agree that a range of 7 -12 dKH ( 2.50 - 4.50 meq/l ) is desirable. When your alkalinity is higher than this - it can prevent you from raising and maintaining your calcium to 350-450ppm. You'll need to lower your alkalinity for sure.
Same holds true somewhat for pH. The higher the pH of the saltwater, the less calcium the water will hold in solution.
pH may be high to continuous use of kalk for the last month or so. If you presently don't have any hard corals or coralline algae growth, I do not see a need to add kalk for all water top offs or dripping it at night.
Doubt if too much surface agitation is causing a saturated O2 level - or greatly affecting your pH.
I don't see a need to load vitamins for future corals either by continuous addition of the Reef Plus. The trace elements present in most good salt mixes normally are sufficient, especially in a tank containing no corals yet.
With the alk and pH high, you may have precipitated some calcium out of solution, without actually seeing the visual "snow" much talked about.
I would discontinue all additives including the kalk for the time being, do a couple few moderate water changes over then next couple months or so to lower your alk and pH, continue monitoring your alk - pH - calcium.
Look for the alk to begin to drop - as it surely will with water changes.
You may find it useful to get a pH test kit or take some of your water to lfs - just to confirm your electronic unit is operating correctly.
I'm sure some others will have suggestions as well, and I wish you much luck.
Brian

 

[predator]

I'm not a technical guy.I have however had great success with my water quality.Lay off the kalk and look into a 2 part calcium buffer.I used kalk for a while and have much better results when I started using a buffer.I personally use Kent Marines Tech CB.But B-ionic makes some good stuff as well.I have had no problems at all.My calcium stays around 500 and my alk is right at 8.2.Just a suggestion.

 

[kenobi]

do this bro
First go with regular Ph test... Go old school when problems occur.
1) Add more CA every day very important.
2) Less feeding
every other day bud, thats why increase in Pho.
You should have no Pho
3) RoDI waste of time whole purpose to pull out Pho and here you are creating it in your tank overfeeding.
Increase CAlicum will drop Alk
Drop alk will drop Ph.Problem solved

 

[kevin01]

Sounds good to me. I think that I will do a 10% and check the alk of the solution before I put it in the tank. I am also going to pick up a Ca additive at the LFS, specifically tailored to raising Ca without raisingthe pH or Alk. Thanks everyone.