Factors that control pH

[A Toadstool Leather]

Aside from CO2 and alkalinity are there any other parameters that can affect pH. Also do open topped tanks not have as much CO2 buildup?

 

[chipmunkofdoom2]

No, CO2 levels and carbonate alkalinity are really the only two effective ways to influence pH in a marine aquarium. The obligatory Randy Holmes-Farley article:

http://www.reefkeeping.com/issues/2007-05/rhf/

If you take a look at the chart in the section Carbon Dioxide and pH, you'll notice that a carbonate concentration of 7 dKh, that of natural seawater, will yield a pH of around 8.2:



This means that in a perfect world with no CO2 buildup, your tank's pH would always be 8.2 (or higher if you maintain higher carbonate alkalinity). We of course don't live in a perfect world; respiring lifeforms in our homes create elevated CO2 levels, which tends to drive down pH in most tanks. Nevertheless, it's an important concept to keep in mind.

A topless tank will generally have better gas exchange. However, if your home has high ambient CO2 levels, promoting better gas exchange may not raise the pH an appreciable amount, if at all.

Some additives like calcium hydroxide and soda ash will raise your pH, but both of these supplements raise your carbonate alkalinity, which may not be desirable. Additives labeled as "pH boosters" or "buffers" should be avoided entirely. Most of these additives are merely carbonate alkalinity supplements and are not long-term strategies for maintaining pH in a reef aquarium.

Image credit to Randy Holmes-Farley and Reefkeeping .

 

[A Toadstool Leather]

No, CO2 levels and carbonate alkalinity are really the only two effective ways to influence pH in a marine aquarium. The obligatory Randy Holmes-Farley article:

http://www.reefkeeping.com/issues/2007-05/rhf/

If you take a look at the chart in the section Carbon Dioxide and pH, you'll notice that a carbonate concentration of 7 dKh, that of natural seawater, will yield a pH of around 8.2:



This means that in a perfect world with no CO2 buildup, your tank's pH would always be 8.2 (or higher if you maintain higher carbonate alkalinity). We of course don't live in a perfect world; respiring lifeforms in our homes create elevated CO2 levels, which tends to drive down pH in most tanks. Nevertheless, it's an important concept to keep in mind.

A topless tank will generally have better gas exchange. However, if your home has high ambient CO2 levels, promoting better gas exchange may not raise the pH an appreciable amount, if at all.

Some additives like calcium hydroxide and soda ash will raise your pH, but both of these supplements raise your carbonate alkalinity, which may not be desirable. Additives labeled as "pH boosters" or "buffers" should be avoided entirely. Most of these additives are merely carbonate alkalinity supplements and are not long-term strategies for maintaining pH in a reef aquarium.

Image credit to Randy Holmes-Farley and Reefkeeping .

I keep my alk around 7.3 dkh. I guess co2 buildup is causing my pH not to be as high as I want. At this point Ive given up on checking pH since my alk is fine. Thanks

 

[chipmunkofdoom2]

I keep my alk around 7.3 dkh. I guess co2 buildup is causing my pH not to be as high as I want. At this point Ive given up on checking pH since my alk is fine. Thanks

You can take steps to reduce the CO2 levels in your tank. If opening the windows and aerating your home is not an option, you can bring outside air into the home. My pH used to top out around 7.9 during the day because I keep my AC running non-stop. I hooked my skimmer up to an outside air source and am using an additional air pump to bring in more outside air. I also drip a weak kalkwasser solution. My pH is now over 8.2 during the day.

 

[A Toadstool Leather]

You can take steps to reduce the CO2 levels in your tank. If opening the windows and aerating your home is not an option, you can bring outside air into the home. My pH used to top out around 7.9 during the day because I keep my AC running non-stop. I hooked my skimmer up to an outside air source and am using an additional air pump to bring in more outside air. I also drip a weak kalkwasser solution. My pH is now over 8.2 during the day.

I like the kalk idea alot. I dont plan on skimming since I only have one fish

 

[Randy Holmes-Farley]

Watch that the pH does not get too high when using limewater without a skimmer (that is, use only as much as you need). When I took my skimmer offline for a few months as an experiment, high pH was the most obvious issue.

 

[A Toadstool Leather]

Watch that the pH does not get too high when using limewater without a skimmer (that is, use only as much as you need). When I took my skimmer offline for a few months as an experiment, high pH was the most obvious issue.

Thanks for the advice. If I use limewater I might dilute it a bit

 

[chipmunkofdoom2]

What is the usual pH reading for your tank? Unless the pH is far outside the range of "normal" for a reef tank (< 7.8, > 8.5) or you have a specific goal for manipulating your pH, it may not be worth chasing a specific number. I had low pH (7.6 at night) and also wanted to increase calcification of my SPS, so it made sense for me.

 

[Randy Holmes-Farley]

What is the usual pH reading for your tank? Unless the pH is far outside the range of "normal" for a reef tank (< 7.8, > 8.5) or you have a specific goal for manipulating your pH, it may not be worth chasing a specific number. I had low pH (7.6 at night) and also wanted to increase calcification of my SPS, so it made sense for me.

IMO, it is desirable to maintain pH at lest above 7.8 and maybe above pH 8.0 to get good growth of some hard corals, coralline algae, and other calcifying organisms..

 

[BigHildy53]

You can take steps to reduce the CO2 levels in your tank. If opening the windows and aerating your home is not an option, you can bring outside air into the home. My pH used to top out around 7.9 during the day because I keep my AC running non-stop. I hooked my skimmer up to an outside air source and am using an additional air pump to bring in more outside air. I also drip a weak kalkwasser solution. My pH is now over 8.2 during the day.

How did you hookup to an outside air source? Did you drill through the outside wall of your house?

 

[Callok]

I was running 2 part, maintaining Alk around 8 dkh, the pH was always hovering around 7.8. I had decent growth of the hard corals. I tried keeping my windows open around the clock, placed fans at my windows with only slight improvement. (pH 7.83)

I started experimenting with Kalk, and finally added a Reef Octopus Kalk reactor about 6 months ago and now use 2 part only to supplement and maintain Alk. The pH is now around 8.1 irrespective of whether the windows are open or not. Coral growth has exploded. I now am making almost monthly visits to my LFS unloading corals that have gotten too crowded. I find this much easier than drilling holes in my walls, and in IMHO much more effective.

 

[chipmunkofdoom2]

How did you hookup to an outside air source? Did you drill through the outside wall of your house?

No, my solution is a bit crude, I'm running a tube through a window. I bought some weather stripping and a 2x2 from a local home improvement store. I cut the 2x2 to size, put the foam weather stripping around all sides, then closed the window on it. I then drilled a hole through the wood and ran a tube outside:



Crude, as I said, but it was a quick and easily undo-able solution to raise the pH. I own an apartment-style condo, so drilling to the outside is not an option for me.

I was running 2 part, maintaining Alk around 8 dkh, the pH was always hovering around 7.8. I had decent growth of the hard corals. I tried keeping my windows open around the clock, placed fans at my windows with only slight improvement. (pH 7.83)

I started experimenting with Kalk, and finally added a Reef Octopus Kalk reactor about 6 months ago and now use 2 part only to supplement and maintain Alk. The pH is now around 8.1 irrespective of whether the windows are open or not. Coral growth has exploded. I now am making almost monthly visits to my LFS unloading corals that have gotten too crowded. I find this much easier than drilling holes in my walls, and in IMHO much more effective.

I agree. If you can get away with just using calcium hydroxide, it's a very easy and simple solution to raising pH. I can't get by on kalk alone, though. I'm dosing organic carbon and can't increase my carbonate alkalinity much higher than 8 dKh. To your point, though, I'm dripping a very weak solution and the increase in pH is significant.