Alkalinity is fine, but pH stays at 8.0

AllSignsPointToFish · Dec 6, 2015

So, the last week the alkalinity has tested around a dKH of 11-12. I know that's a little high, but it has come down some. I assume it's a little high right now because I don't have any fast growing corals or coralline algae that would remove dissolved carbonates from the water, and there was a lot of fine carbonate silt when I added the live sand.

However, the pH has remained a steady 8.0 during the entire time. I'm using a colorimetric test, so it's not the most accurate, and I won't have a pH probe until I get my controller. I don't understand how I can have a pH of 8 with such high alkalinity. Any ideas if this is bad or if there is something keeping my pH from coming up to around 8.2-8.4?

The test reagents are all brand new and not expired. Should I look at adding some kalkwasser to get the pH up a little?

By the way, I do not have a magnesium test, so I have not had a chance to test for magnesium. I assume magnesium has little effect on pH.

jsker · Dec 6, 2015

Try a different test kit for ph. It could be your test kit. I was having the same issue bought a new kit and now testing fine.

AllSignsPointToFish · Dec 6, 2015

Yeah, I guess I'll have to order one. I don't have many options for a LFS.

ddgtr · Dec 6, 2015

Im having the exact same issue. I test with API, and verified my findings with the fish store.

At water change, my alkalinity is at 11 and ph at 8.2. 10 days later, ph is at 8 or even 7.9 and alkalinity at 10. I use seachem's buffer to bring the ph up to 8.2, but at the same time the alkalinity goes to 12. Calcium at 400 to 440 without dosing. I dose MG but don't even bother to test since the Elos kit I have gives me stupid readings.

This is such a hard topic to get concrete answers to, I've read a lot but people start recommending articles with graphs and that's where I get lost.

Newb73 · Dec 6, 2015

Its winter. Excess C02 in your home will push it down a bit. Worse in small homes, enclosed rooms and homes that use gas (non-vented) heat.

I have also observed that insufficinent lighting has an impact. I can turn my Hydra's down to 40 or 45% and a fairly decent drop in PH over running them at 55% or 60%. If you think it is C02 you can add a scrubber to your skimmer intake. You can also alleviate it by running kalk your ato, although i probably would not do that if your alk is already 11 or 12.

I have a fairly large house but run non vented gas logs in the winter. Even with an alk of 7 or 8 i get a PH of 8.15 to 8.3. I do however, keep a co2 scrubber at the ready for when it gets really cold and the gas logs get run more etc.

The last thing you might want to look at is circulation. Anectodal only but i find running my pumps in the higher end of the sps recommended amount seems to improve ph. The only other thing i can think of that miht be helping me keep such a high ph is my avast marine swabbie and locker which keeps the skimmer running at 100% efficiency ...100% of the time thus keeping the doc very low.

ddgtr · Dec 6, 2015

Thanks much for the scrubber tip, I'll definitely try it. I do have a fairly large house, 2,800 sqft but it's pretty well sealed so not much outside air gets in. I'll try this first.

As for the lighting, I am also running two Hydra 52 HD. I have to tone the whites down to about 10% and blues to 60 to get good color out of my corals, otherwise they look pale. I have had the whites higher but did not notice a difference in PH. Thanks again for the help!!

Downbeach · Dec 7, 2015

C02 is what's affecting your pH, as mentioned a scrubber will help, although a pH of 8 is fine. I ran a reef tank for many years with my pH running between 7.8 and 8.1(measures with a calibrated probe). Can you run an air line from your skimmer's intake to an outside air source? The scrubber will help, but the media may need frequent changing, depending on the amount of CO2, and is relatively expensive.

Randy Holmes-Farley · Dec 7, 2015

ddgtr said:
This is such a hard topic to get concrete answers to, I've read a lot but people start recommending articles with graphs and that's where I get lost.

OK, I agree it it may seem complicated to some folks, but it is actually one of the easier chemistry concepts to fully understand.

pH is determined mathematically by CO2 levels in the water and the alkalinity. Nothing else. (well, except very minor impacts of salinity and temperature).

If alkalinity is normal or high, and pH is low, the only possible explanation is elevated Co2 in the water, and that most often comes from elevated CO2 in your home air.

That said, there is NO reason to be concerned about pH 8.0. I would estimate that more than half of all reef tanks spend a considerable amount of time at pH 8.0 or lower.

There are a number of ways to raise pH is someone desires it for some reason, which can include bringing in more fresh air to your home (like an open window), more fresh air to the tank (like an air line from outside to a skimmer inlet), using a CO2 scrubber on a skimmer inlet, depleting CO2 in the tank buy using limewater (kalkwasser) or a large, well lit refugium.

This has more:

PH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

AllSignsPointToFish · Dec 7, 2015

The refugium is large and well lit, but the Chaetomorpha was just added on Friday and has yet to take hold.

I had doors open last night, but I didn't retest pH last night. All appliances are electric, I.e., no gas fired equipment.

Another guy I work with also has the same problem with with excess CO2, so I wonder if it has something to do with the area. interesting....

Randy Holmes-Farley · Dec 7, 2015

AllSignsPointToFIsh said:
The refugium is large and well lit, but the Chaetomorpha was just added on Friday and has yet to take hold.

I had doors open last night, but I didn't retest pH last night. All appliances are electric, I.e., no gas fired equipment.

Another guy I work with also has the same problem with with excess CO2, so I wonder if it has something to do with the area. interesting....

It is a problem for many folks. Homes and buildings are designed to be quite tight, and allowable CO2 limits in many buildings could push pH down by more than a half pH unit from normal.

AllSignsPointToFish · Dec 7, 2015

Wow! I did not know that. thanks!

Randy Holmes-Farley · Dec 7, 2015

AllSignsPointToFIsh said:
Wow! I did not know that. thanks!

A doubling of CO2 in the air will drop the pH of seawater equilibrated with it by 0.3 pH units.

Normal outdoor CO2 is about 350 ppm.
As to indoor CO2 levels, from the discussion below, air with even 1000 ppm is considered adequately ventilated. The pH of seawater in that air will be about 0.46 pH units (log (350/1000)) lower than normal.

https://en.wikipedia.org/wiki/Indoor_air_quality

from it:

"To eliminate most complaints, the total indoor CO2 level should be reduced to a difference of less than 600 ppm above outdoor levels. The National Institute for Occupational Safety and Health (NIOSH) considers that indoor air concentrations of carbon dioxide that exceed 1,000 ppm are a marker suggesting inadequate ventilation.[20] The UK standards for schools say that carbon dioxide in all teaching and learning spaces, when measured at seated head height and averaged over the whole day should not exceed 1,500 ppm. The whole day refers to normal school hours (i.e. 9:00am to 3:30pm) and includes unoccupied periods such as lunch breaks. In Hong Kong, the EPD established indoor air quality objectives for office buildings and public places in which a carbon dioxide level below 1,000 ppm is considered to be good.[21] European standards limit carbon dioxide to 3,500 ppm. OSHA limits carbon dioxide concentration in the workplace to 5,000 ppm for prolonged periods, and 35,000 ppm for 15 minutes. These higher limits are concerned with avoiding loss of consciousness (fainting), and do not address impaired cognitive performance and energy, which begin to occur at lower concentrations of carbon dioxide."

AllSignsPointToFish · Dec 7, 2015

Very interesting. It's pretty hard to argue the tank is not in equilibrium with the ambient indoor air

I may still try another pH measurement methodology just for grins.

Randy Holmes-Farley · Dec 7, 2015

AllSignsPointToFIsh said:
Very interesting. It's pretty hard to argue the tank is not in equilibrium with the ambient indoor air

I may still try another pH measurement methodology just for grins.

Sounds good. A pH meter which you can calibrate and/or check for proper calibration is a good bet.

AquamanE · Dec 7, 2015

Downbeach said:
C02 is what's affecting your pH, as mentioned a scrubber will help, although a pH of 8 is fine. I ran a reef tank for many years with my pH running between 7.8 and 8.1(measures with a calibrated probe). Can you run an air line from your skimmer's intake to an outside air source? The scrubber will help, but the media may need frequent changing, depending on the amount of CO2, and is relatively expensive.

I agree on all accounts.