2 novice questions about ph/kh

[dclegern]

sorry to ask this. but need advice..
The tank has been running perfect and beautiful most of the year, but now the ph and kh are both low.
I'm using a buffer to raise the ph and stabilize kh, but within a day or two it's back down a bit.

any ideas on what is causing such a swing?
and should I be taking my charcoal bags out while I dose?

[hobogato]

could be stagnant air causing a buildup of CO2. try opening a window and letting some fresh air in.

[BSJF]

Exact test readings please:
What is your magnesium at?
What is your calcium at?
What is your alkanity at?

What exactly are you using to buffer?

What type of salt do you use? What are the alk, calc, and mag of it when it is mixed up read for use?

[Richard]

Tell us what your kh is. If the alkalinity is good but the ph is low then high CO2 is really the only thing it could be. This could be from a calcium reactor or CO2 buildup in your house like Ace said. This is the time of year when people tend to build up CO2 levels in their house since ac's and heaters aren't running much.

[dclegern]

calc @ 480.
alk @ 1.8.
kh @ 160ppm
ph @ 8
mag.............I don't usually test for.
nitrate/nitrite/phosphate all at 0.
good circulation in the tank, plenty of LR, sump w/ skimmer,..................just odd after 2 years I have a lingering ph/kh lull.

[BSJF]

Calcium is a bit high, ph is fine and so is your kh and alk. Most salts are low in magnesium. If you can't keep your calc and kh stable, mag is usually the cause.

What is your kh and ph typically at?

[dclegern]

kh usually @200
ph usually @8.4

[BSJF]

I would guess that your calcium is usually lower than it is right now then. If you raise your kh with your calc as high as it is, you will get a snow storm in the tank. Did you change salt mixes recently? Some are higher in calcium than others and batches can even be different.

This is a good article about ph, and how calc and alk affect it.

http://www.reefkeeping.com/issues/2004-09/rhf/index.php

[BSJF]

http://www.reefkeeping.com/issues/2002-04/rhf/feature/index.php

Another must read. You may not understand everything these say, but reading them anyway will help you gain a much better understanding of what is going on. This one has a few tables that are good quick references. You will probably also need a reference for converting your test kit readings from ppm to meq/L.

[BSJF]

http://www.advancedaquarist.com/issues/nov2002/chem.htm

One more of my favorites. This helps you understand when everything is in balance and what to do if it isn't.