PH Confusion. Please help

[andrewsk]

Hi guys. I am hoping you can give me some advise on what to do.

I am new to the hobby and have been playing and testing PH levels. I have 2 test kits and a PH Pen.

When I first make RO/DI water and test the PH it bottoms out on the PH test chart meaning it is below 7.4. PH pen shoes just below 7.

Next I add Instant Ocean Salt and retest the PH. 8.2 on all tests. Great.

Next I add a buffer (Seachem 8.3) according to the directions (1 teaspoon per 20 gallons). When I test the PH it is off the charts and PH pen shows 9.8??

Then I tried, RO/DI water, Instant Ocean and some Kalk with no buffer. 9.8 again.

What am I missing here? Should I be adding way smaller amounts than the directions?

Right now, I am sticking with plain old Instant Ocean and RO/DI until I can figure this out.

My tank is at 7.9 to 8.2 depending what test kit I am using.

Any help is greatly appreciated as I am lost!

[vanreefer]

7.9 - 8.2 is fine.... I would stop using the buffer... the important thing with pH is stability

[reeferaddict]

Yi yi yi! Correct that man.... (Not trying to be argumentative Dano, just what you're saying can be misleading...) stability IS key to PH.... but to get stability your water should be running at an alkalinity of 8 - 11 dKH... (2.5 - 4 mq/L) Same values... just different ways of expressing it.... When salinity is at 1.021 - 1.026, Alkalinity is at the aforementioned levels and Calcium is between 380 and 420 ppm then PH should be around 8.2... which is perfect... About the only thing that makes this drop is too much C02 in the system.... or a rotting animal carcass...

FYi... to make PERFECT mixed Seawater with IO salt.... get some Kent Osmo-Prep Marine.... follow the directions and your mix will be (at SG of 1.024) Calcium 410ppm, dKh 10, and PH 8.2... been doing it that way since Janary and it works every time.... but check with test kits... this is assuming your RO/DI water has a TDS <10ppm.

You won't be able to get any kind of accurate reading for PH in pure water as there are no available ions to buffer the water. The water will take on the PH of the salt mix... When you add buffer of any kind...(including Kalk) you are adding bicarbonates very high in PH... until these pair off with carbonates.. (C02), you will definitely get a spike in PH... try aerating the water and test again in 24 hours and I think you'll see a PH of 8.3 to 8.4...

This should also explain why C02 drops the PH... carbonates bind with available bicarbonates... (buffer) to reduce the overall buffer capacity of the water leaving the remaining C02 to form other ionic bonds with the end product being carbonic acid... thus dropping PH... when alkalinity is maintained, this happens at a rate that keeps PH at proper levels... Likewise too high an alkalinity will cause bicarbonate precipitation resulting in too high a PH...

I hope this gives a little insight.... some of my terminology may not be correct but the concept is...

Now maybe even I can understand this!!!

FYI - I monitor my PH with a monitor.... check Alk almost every day... and Calcium at least twice a week...

[reeferaddict]

Sorry.... if you switch "carbonate" and "bicarbonate" around I might have this right.... anyone?

[Beverly]

I would stop adding buffer to the new salt mix, as well.

Here are my favourite links on reef chemistry to help you better understand the complex chemical reactions going on in your tank:

Aquarium System Volume Calculator:

http://home.comcast.net/~jdieck1/volcalc.html

The Reef Chemistry Calculator:

http://home.comcast.net/~jdieck1/chem_calc3.html

What is Alkalinity?

http://advancedaquarist.com/issues/feb2002/chemistry.htm

Calcium:

http://advancedaquarist.com/issues/mar2002/chem.htm

Magnesium in Reef Aquaria:

http://www.advancedaquarist.com/issues/oct2003/chem.htm

How to Select a Calcium and Alkalinity Supplementation Scheme:

http://www.advancedaquarist.com/issues/feb2003/chem.htm

The Relationship Between Alkalinity and pH:

http://www.advancedaquarist.com/issues/may2002/chem.htm

Solving Calcium and Alkalinity Problems:

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

High pH: Causes and Cures:

http://reefkeeping.com/issues/2005-03/rhf/index.htm

Low pH: Causes and Cures:

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

[reeferaddict]

Thanks Beverly.... I was looking for those....

I think this is the best one... read, understand, and execute this, and you will have no PH problems...

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

[Beverly]

Thanks Beverly.... I was looking for those....

You're welcome :biggrin:

What the heck are you doing up at this time of night :eek: On the other hand, what am I doing at this time of night :razz:

[reeferaddict]

Uhm... trying to get my Alk and Ca up... :mrgreen: I put in a Phosban reactor, everything is starting to take up Alk and Calcium like crazy! 360.... 375.... maybe tomorrow or the day after I get it back to 400... SLOWLY now... don't knee jerk & over react... :rolleyes: I even cranked out the second test kit tonight... then the 3rd... I'm gonna have to plumb in the reactor this weekend...:eek:

[Beverly]

Uhm... trying to get my Alk and Ca up... :mrgreen:

At least your tank is getting some attention :biggrin: I'm sitting here editing another video :eek: :razz:

[Johnny Reefer]

.... I would stop using the buffer...
I would stop adding buffer to the new salt mix, as well.

I third that.

Cheers,