PH in new tank


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Jun 26, 2023
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I am just getting started with my first saltwater display tank. A true saltwater noob. So currently my main display tank is setup with nothing but sand and rock in it. I'm slowly getting all the equipment running while waiting for the sand storm to dissipate. I do not have the lights on. I have added the tropic marin pro-reef salt mix and my SG is about 1.026. Yesterday I calibrated my ph probes (Neptune Apex), in both my main tank and my QT. My QT is currently hosting a pair of clowns and a royal gramma. No sand, rock ... just pvc. Anyway, the PH in the main tank was 7.84 and the QT was 7.88.

I know (or have read) enough to know to not chase the PH, and that is fine. With no fish or coral, I would have expected the PH to be in the 8-8.4 range like the salt mix states. I do understand to some extent that carbonic acid is often (or perhaps the only) cause of PH to decrease in a situation like this. I am using RO/DI water with my salt mix, just in case that was a thought. Last night I opened up the patio door and some windows, but that didn't change the PH at all. I am currently solo in a house, and I doubt CO2 is a problem, but just wanted to be sure.

I am currently running my return pump, two MP40s and a GYRE (pointed somewhat to the surface) to cause a fair amount of surface agitation. I wouldn't "guess" that this is the problem, but I am open to the idea. Today or tomorrow I am thinking about getting the skimmer running just to see if it alters the PH at all.

Am I missing something obvious? I guess I read some articles/dms on here where accuracy of the PH probes has been called into play. I have a Hanna PH probe and checked that this morning 7.92 vs 7.86 on Neptune Apex. So more than likely I the probes are probably pretty similar. So, I don't think it is a probe issue.

Is there anything else to consider? I am not freaking out about it or anything, but would like to understand why my PH is on the low side of "normal".

Thanks in advance.

Randy Holmes-Farley

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The pH is driven by the alk and the CO2 level, which is often strongly contributed by the air in the room.

There are many ways to raise pH, but I would not bother with any of them until you gave hard corals and want them to grow faster.


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