Still Chasing pH?

http://www.reefkeeping.com/issues/2004-05/rhf/index.php.



the pH range from 7.8 to 8.5 is an acceptable range for reef aquaria, with several caveats. These are:

1. That the alkalinity is at least 2.5 meq/L, and preferably higher at the lower end of this pH range. I base this statement partly on the fact that many reef aquaria operate quite effectively in the pH 7.8 to 8.0 range, and that most of the best examples of these types of aquaria incorporate calcium carbonate/carbon dioxide reactors which, while tending to lower the pH, keep the carbonate alkalinity fairly high (at or above 3 meq/L.). In this case, any problems associated with calcification at these lower pH values may be offset by the higher alkalinity.

So yeah you can have a low pH and an acceptable ALK level. Mr.Randy Holmes-Farley, makes it so much more understandable then I ever could.

I partially agree with Guitar in that some tanks do have a chronic low pH that adversely affects the entire health of the system. Those tank types commonly have higher C02 concerntration, smokers, tanks in basements, homes closed up to maintain a warm environment.

Correction with buffers alone though can lead to bigger problems then a chronically low pH. Not the best the intervention for newer hobbyist.

 

Agree, there are so many factors that play into ph. When people have issues with Stoney corals, it's often bc of ph swings.

 

Ok, I'll check my Ph tonight maybe. The rare times I check, usually around 8.0ish.
I just feel like my 72" long C2C overflow keeps this WNL. = Within Normal Limits

 

I know that it is not advised to "chase" pH and a pH of 7.8 is generally considered quite acceptable and no reason to mess with it. Global ocean acidification and reduced pH in our homes are caused from the same thing, CO2 levels (more or less if alk is in the NSW range). Now if we are worrying about global impact of CO2 why shouldn't this be of concern to tanks in our homes that if sealed up, have elevated levels of CO2? I am asking this because there have been, and probably will be more, studies of coral growth under higher CO2 concentrations which translate to low pH. Doing a quick search of studies it appears that low pH in the 7.8 and 7.9 region does impede coral growth. While the coral might still live, it appears to me that lower pH that has been recommended as acceptable does slow growth. Considering all the arguments we have over what goes coral faster with lights, calcium and alk levels, amino acids and such it would seem that having published results that show reduced growth should be more of an issue possibly revising the range of pH we consider acceptable for coral in our home aquaria if we want growth and color (or lack of bleaching). Here are just two studies I found:


Bleaching was increased and calcification decreased at 7.85-7.95 at temps we use in the hobby:
Ocean acidification causes bleaching and productivity loss in coral reef builders

Not as good for our purpose since the low pH was lower than what we call acceptable but still interesting as the results look pretty linear and one could use that for pH of 7.8 and show lower growth (not the best science I know):
http://sigarra.up.pt/icbas/pt/publs_..._gdoc_id=11431


I am wondering if it's time to revise reef pH recommendations or at least clarify a pH of 7.8 is acceptable but most likely results is slower coral growth with possibly greater bleaching.

No, I don't think one should chase pH, but if you can raise alk slightly and see if there is a positive pH impact or run a skimmer line to a window it is worth the consideration. There is clearly scientific evidence that pH of under 8 negatively impacts our coals.

 

I doubt fish really care but I do believe with a PH of 8.2 coral growth is better. I'm not saying chase the number but if you have very low PH you may get better growth if remedied.
Mine is usually 7.7-8.1. I would like a little higher. Also I calibrate about every three months the probe seems to be off by about .2 by that time.