alkalinity, calcium and magnesium and their relation to ph

[RoTTen2TheCore]

Hello all,
So I have been under the impression that if your calcium, alkalinity and magnesium levels are all in the right place, then your ph should automatically be as well (hence the 2 part cal and alk buffers out there). However, I often find my ph and the ph of my friend's tank to always be dropping in ph and we always have to throw in some buffer every 2-3 days. Both of our tanks have 0 phosphate 0 nitrate and cal, mag and alk all in the proper range.

Can anyone enlighten me or point me to a good article about how these three elements play with ph and or how to keep my ph stable while dosing these elements?

Also, my friend has a doser. Is it a good idea to mix the powder buffer with RODI water, put it in a container and hook it up to his doser to provide a steady ph for a longer period of time?
Thanks!

[Reefmedic79]

pH fluctuates constantly during the day, it's best not to chase the pH and maintain the "Big 3" you mentioned. If those parameters are in check I wouldn't worry too much unless it's extremely low.

What is your pH, and are you testing at the same time of day every time?

Low pH could be a result of high CO2 levels in the tank.
Do you have a skimmer?
Sump or HOB equipment?
Glass tops on the tank?
How much flow do you have in the tank?

[Sugar Magnolia]

Check here - http://reefkeeping.com/issues/2004-09/rhf/index.htm

Also, a link to the rest of the reef chemistry articles - http://reefcentral.com/forums/showthread.php?t=2127046

[Megatrev62]

Go to reef chemistry here.

[downbeach]

I wouldn't continue to add the pH buffers, since its effect will only be temporary, and all it really does is raise your alk. Any time of year your house is closed up due to weather, you will have an accumulation of excess CO2 in the household atmosphere, which through gas exchange, will elevate the CO2 in your system and lower your pH. As long as it doesn't get below around 7.8 I wouldn't worry about it. There are however a couple things you could do to keep it up a little: run a CO2 scrubber on your skimmer's intake, run an air line from your skimmer to an outside source of air, or start using kalk in your top off water. If you/your friend are on a dosing schedule, you may have to make adjustments if you start using kalk.

Here is a little more reading about pH and its diurnal change:

http://reefkeeping.com/issues/2007-05/rhf/index.php#6

[RoTTen2TheCore]

My ph, without the help of buffer, drops down to 7.8.
I do have a skimmer and I do test the ph at different times of the day.
But regardless, when it drops, it doesn't go back up.
I don't think it is a co2 issue since I have pretty good ventilation/fresh air going through my apartment and we are only 2 people in a 1400 square foot area.
The flow in my tank is fairly high (almost 40X)

I may start using Kalk, i assume that when you mention that there will be dosing ajustments, you mean cut down on the calc since the kalk provides it already?

[thegrun]

7.8 is fine.