Ph fluctuation

[Fdnavy]

Is this normal? My Red Sea kit typically reads 8.0 my apex averages 7.79 but fluctuates between 7.65 and 7.9 through out the day. The lowest is at night which I understand as normal. I run a 90 gallon tank with 35 gallon sump. A skimmer, 1 3000gph gyre at 70%, 2 return nozzles, a fuge with a 100 watt equivalent 6500k led bulb running opposite a radion gen 2 xr30. My tank is still cycling and there's nothing live other than a chaeto ball I just added to the fuge.

 

[Reefable]

Seems like your tank is pretty new. It is normal for the Ph to fluctuate in decimals. I think it will settle down on its own.


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[karimwassef]

7.65 is a little on the low side. are you buffering with kalk or use a protein skimmer?

 

[Fdnavy]

Yes I am using a protein skimmer and no, I am not buffering.

7.65 is a little on the low side. are you buffering with kalk or use a protein skimmer?

 

[Optionman]

A previous graph of mine. I run CArx and skimmer.


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[karimwassef]

More importantly... how's your Alkalinity? I realize it's a new tank but it doesn't hurt to start asking the right questions.

 

[fishchef]

In a SW system ph is not that critical. Its dKH that you need to watch. If dKH is in line ph will follow. Ph fluctuates during the day and night by nature. If you have a refugium on a reverse lighting schedule it will remain more stable.

 

[Fdnavy]

I'll start checking alk. I hadn't been checking that yet. I believe part of the issue is co2. My house is buttoned up pretty tight year round. This time of year the heat doesn't come on as much which means less circulation. Today while cooking dinner the ph dropped like a rock from 7.92 to 7.51 started almost Imediately once the stove and burners were fired up. I switched heat pump to circulation mode and it started to rise.

 

[karimwassef]

you should have a source of fresh air hooked up to your skimmer.

But again, it's not about the pH as long as you're over 7.8

 

[Optionman]

The more large plants you can add to the room the better. Crack open window when using stove.

Agree that stable Alk is target.


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[ReefsandGeeks]

Not to steal the thread, but I have a similar situation currently. I've always just maintained Alk, Ca, and Mag and never tested pH as it's often said to not be important if the other numbers are in the safe range and stable.

My perameters are stable at :
Salinity: 35ppt
Mag: 1340ppm
Alk: 8.5-9 Dkh
Ca: 440ppm

But I recently checked my pH and am getting low 7s, like 7.2ish, maybe 7.5 at most during the day. Should I be concerned that pH is low even though the other numbers are in a healthy range and stable? My tank is located right in the middle of the house so running the line from my protein skimmer to outside isn't an option for me. My house was built in the '30s so I'm sure it's not air tight. Should I be purposely trying to raise alk to 10ish in an effort to keep pH up?

 

[bertoni]

That pH range is acceptable for the most part. I'd try to keep it at 7.8 or better, if possible, but that might be difficult. The stove will drop the pH, as you've seen, so a carbon dioxide scrubber might be worth considering if the house has a very low air exchange rate. I don't think that plants will help much in the average setup. They will lower the pH at night when there's no photosynthesis happening.

 

[karimwassef]

If your pH is in the low 7s and Alk is 9... I'd check your measurements. Your probe or test kits are probably off.

Just for fun, I decided to see what it would take for this to happen.

at 80F, high salinity of 40, and 30inHg pressure, a pH of 7.4 would yield an alkalinity of 9.3dKH only if the CO2 was at 4000ppm...

fresh air is ~450-500 ppm and indoor air is 750-1000 ppm... so definitely, a probe is off.

 

[Fdnavy]

It was definitely a co2 issue. I turned on the circulating fan for my hvac system and I have been steadily climbing since last night. 7.91 and rising.

 

[Fdnavy]

Posted the wrong picture. This is updated graph.

 

[karimwassef]

looks better!

 

[ReefsandGeeks]

That pH range is acceptable for the most part. I'd try to keep it at 7.8 or better, if possible, but that might be difficult. The stove will drop the pH, as you've seen, so a carbon dioxide scrubber might be worth considering if the house has a very low air exchange rate. I don't think that plants will help much in the average setup. They will lower the pH at night when there's no photosynthesis happening.

I looked into a CO2 scrubber, and although I think it would be a good fix, I'm afraid to buy another piece of equipment that has an added weekly/monthly cost for expired media.

I do carbon dose (vinegar) and I know that can lower pH. My vinegar dose is at 70mL/day on a 65 gallon tank. Would I benefit from switching to vodka or another carbon source in an effort to bring my pH up to at least 7.8?

 

[bertoni]

The effect of the vinegar should be fairly small and will be temporary. The vodka will be digested into an organic acid, as well, I believe, and the end result will include some carbon dioxide, so it'll lower pH a bit as well, although the effect probably would be spread over a longer period.