pH getting too low?

[john1979]

I bought an Apex Lite controller and it has been running for a couple of days. After looking at some of the data I found that my pH is getting pretty low overnight. It's getting to a high of 8.3 around 4:00 pm, and a low of 7.75 around 7:00 am.

From all of the reading I've done on this site, it seems like those numbers are OK, but I wanted to check with all of you experts!

John

 

[Capt_Cully]

I wouldn't jump to react to the numbers alone. If you want to verify the numbers you can test the water to be sure those numbers are real. If the inhabitants are happy and growing, you're probably fine. Personally those numbers dont scare me, but ths 7.75 for extended periods definitely makes me nervous enough to keep track of it.

How long has the tank been running? If everything's been fine up to now, no reason you should suspect anything is dramatically wrong now.

 

[Capt_Cully]

I wouldn't jump to react to the numbers alone. If you want to verify the numbers you can test the water to be sure those numbers are real. If the inhabitants are happy and growing, you're probably fine. Personally those numbers dont scare me, but ths 7.75 for extended periods definitely makes me nervous enough to keep track of it.

How long has the tank been running? If everything's been fine up to now, no reason you should suspect anything is dramatically wrong now.

 

[john1979]

The tank has been running for almost a year, and everything seems pretty healthy. I feel like the numbers are OK, but I thought I'd just check here and get a second opinion!

Thanks for the help!

 

[Capt_Cully]

I'd say you're good!

 

[SquidwardTentacles]

Use a second test. Last thing you want is a pH of 10 because you had bad data.

 

[tmz]

The swing is not an issue. A 7.8 is about the bottom i'd tolerate though. At 7.7 or less some coral skeletal mass and other calcium carbonate can begin to dissolve depending to an extent on the alkalinity.

 

[john1979]

tmz - What would you suggest I do to raise the pH to keep it from dropping to 7.7? My calcium hovers around 440, and my Alk is around 8 dKH. I also add Kalk to my top-off water. I don't use 2-part or any other additives.

Any suggestions?

 

[briangsxr1000]

Could just run your top off over night with the kalk....That is what I do now. But I was battling high PH. That should help it stay more stable.

 

[SkiFletch]

Off-cycle refugiums are the best way to control photosynthetic CO2 swings like that IME

 

[tmz]

The ph drops because CO2 in the water is high. That's why absent CO2 consuming photosynthetic activity the ph drops at night.,even in nature. Essentialy the CO2 free up H+ in the water.

To raise it more photosynthesis can help,such as from a good sized macroalgae refugium.

CO2 enters the water from the surrounding air or is produced in the tank by respiring organisms including bacteria degradng organic material. To raise it more surface agitation and open water can help if the room air is not low in CO2. Dripping kalk as you do helps because CO2 is consumed as the hydroxide in the calcium hydroxide( kalk) binds with CO2 to form carbonate alkalinity. if the room air is high in CO2 ,more fresh air in the room helps or a CO2 scrubber hooked to the skimmer air intake can raise it .