Hyper-low pH (7.1) during cycling?

[BTBarney]

Hi all, I’ve not seen this before…

I have been cycling my waterbox 6025 (~150 working gallons) for about a month now. Dried ex-live rock from a past tank of mine (left in the sun for ~6 months), no lights installed, 1 inch sand bed (100lbs caribsea arag-alive). After running for 1 week, I added Brightwell Microbacter Start XLM (followed instructions) and have my little clownfish in there eating and excreting. Tank has been with this fish for about 3 weeks now. Salifert total ammonia test is not zero, but is less than 0.15 mg/L NH3 / NH4. Barely detectable.

As mentioned in the title, my pH is hovering around 7.1 with little diurnal fluctuation. I have calibrated the probe three times, and tried a different probe… all agree on 7.1. Alkalinity is also being consumed at a rate of about 1dKh/day... I am dosing to keep it at ~8dkH. I am running my skimmer 24/7 with a recycling CO2 scrubber on it, and about 1/3 of the media has changed purple since I installed it. The house is fairly closed up due to California heat and fires, but a 24-hour test of open windows and fans on did not change the tank pH by much, about a 0.1 unit increase to ~7.2

I guess my question is should I be worried? I’ve never seen it this low, and I wonder if I am locking all available NH3 up into NH4 (extra H ions from low pH), thus stalling out the cycling…

 

[Pistondog]

Tough circumstances. Have lfs verify ph.
Are you dosing kalkwasser? That raises alk and ph I think.

 

[brandon429]

Do Randy’s bubble test sample approach to have a comparison for ambient co2 effects here, I read that as a starting assessment point in a similar thread

 

[brandon429]

Your cycle will not undo

there has never been an instance of an undone cycle on reliable testing (seneye) even with that current challenge. cycles are set and forget


you have enough surface area and the shift here if not killing your reef isn’t going to kill filter bacteria it simply takes more to sterilize than that. worry about coral skeleton loss, I’ve managed to set back my ten year old war coral and pit out parts of the old skeleton underneath the polyps by ignoring pH a long time and putting off tank care, which in a tiny pico amounts to acidification stress mass loss.

even after tan conversion above .015 nh3 beats most quarantine setups currently running as a constant

 

[Gedxin]

What salt are you using? What water are you using to mix your salt? That's super low pH and seems like there's something else going on that is contributing. If you mix your salt separate from your tank and test the pH, what's it at?

 

[Uncle99]

I never got any good reads of PH off probes, so I tossed it and just use the simple API PH test kit now.
In newly mixed saltwater, the PH should be around 8.4 so put your probe in that and see what it reads.

 

[BTBarney]

Thanks for all the replies. Here are responses:

Dosing BRS Soda Ash, 2mls per hour on the hour. Should raise pH with moderate contribution to alkalinity.

I did the bubble test (1 hour aeration outside) and the pH of the water was 7.6. Checked the calibration of my probe (I have a supply of pH 7 and 10 buffers, yay!) and the probe is spot on those solutions, so I believe the probe.

Red Sea blue bucket, made with RODI I produce with my BRS unit in good working condition. 0 TDS after the 6 stage filter (mechanical, carbon block, 2 75gpd RO filters in series, cation resin, anion resin, mixed bed resins). I will make some new water soon (outside!) and test it before using to see if it mixes at pH ~8.2 - 8.4 as it says on the bucket.

Don't have a backup pH test kit - though I am tempted to bring a sample to my work lab and test it on the DL.

 

[Randy Holmes-Farley]

I'm still not convinced the pH 7.1 is/was real. The rock and sand would dissolve and raise both the alk and pH.

pH is not an attribute of a salt mix alone, so no bucket label is useful. The pH after mixing depends only on the alk and the CO2 level of the air it is equilibrating with.

 

[Garf]

Hi all, I’ve not seen this before…

I have been cycling my waterbox 6025 (~150 working gallons) for about a month now. Dried ex-live rock from a past tank of mine (left in the sun for ~6 months), no lights installed, 1 inch sand bed (100lbs caribsea arag-alive). After running for 1 week, I added Brightwell Microbacter Start XLM (followed instructions) and have my little clownfish in there eating and excreting. Tank has been with this fish for about 3 weeks now. Salifert total ammonia test is not zero, but is less than 0.15 mg/L NH3 / NH4. Barely detectable.

As mentioned in the title, my pH is hovering around 7.1 with little diurnal fluctuation. I have calibrated the probe three times, and tried a different probe… all agree on 7.1. Alkalinity is also being consumed at a rate of about 1dKh/day... I am dosing to keep it at ~8dkH. I am running my skimmer 24/7 with a recycling CO2 scrubber on it, and about 1/3 of the media has changed purple since I installed it. The house is fairly closed up due to California heat and fires, but a 24-hour test of open windows and fans on did not change the tank pH by much, about a 0.1 unit increase to ~7.2

I guess my question is should I be worried? I’ve never seen it this low, and I wonder if I am locking all available NH3 up into NH4 (extra H ions from low pH), thus stalling out the cycling…

You got any borax in the kitchen?

 

[BTBarney]

I'm still not convinced the pH 7.1 is/was real. The rock and sand would dissolve and raise both the alk and pH.

pH is not an attribute of a salt mix alone, so no bucket label is useful. The pH after mixing depends only on the alk and the CO2 level of the air it is equilibrating with.

Entirely likely with more data... probe now reads 6.98! I am a laboratory scientist so I know how to calibrate a pH probe . I winder if there is some other factor, like noise from nearby wires in the cabinet or an Apex Head unit issue. Tomorrow I will take the probe down (leaving it submerged, never run these dry!) and wait a few days, then calibrate with the probe unplugged. I've already done this once, and tried two separate Apex pH probes with the same result, but I'll keep trying here.

BTW: I'm doing manual calibrations in apex.local, and the probe reading I get in pH 7.00 buffer is stable and unchanging after 10 minutes at ~830. Most people report this number in the low 700s. This is true again for both probes I've tried, so it is less likely a probe issue.

 

[Randy Holmes-Farley]

Apex does seem to have problems with accurate pH. Not sure why. Measuring in a cup away from the tank is a good first step.

Assuming the pH correctly reads both buffers in a cup, and the tank water reads pH 7, then it is either a calibration buffer problem, or an actual low reading.

The fact that open windows didn't help is another indication of a measurement issue.
For pH to really be that low in aerated seawater implies that the CO2 level in the home is dangerously high, or the tank is hardly aerated at all.

 

[arking_mark]

Assuming your tank has ventilation, decent aeration, and reasonable Alk levels, 7.1 NBS pH doesn't pass the common sense test. Your indoor air quality would have to be unsafe for people and pets.

Aquarium pH Distilled

I just wanted to share my understanding of reef pH which is mostly based on: Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com Many would agree that reef tanks can be successful with pH between 7.8 – 8.5 NBS and daily swings as great as 0.5 NBS. Natural pH levels in our ocean...

www.reef2reef.com

 

[BTBarney]

Assuming your tank has ventilation, decent aeration, and reasonable Alk levels, 7.1 NBS pH doesn't pass the common sense test. Your indoor air quality would have to be unsafe for people and pets.

Aquarium pH Distilled

I just wanted to share my understanding of reef pH which is mostly based on: Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com Many would agree that reef tanks can be successful with pH between 7.8 – 8.5 NBS and daily swings as great as 0.5 NBS. Natural pH levels in our ocean...

www.reef2reef.com

Thanks all for the input - I agree the number doesn't make sense. I'll take it up with Neptune to see if they have some ideas/solutions. I'd only ever seen people reporting 7.4-ish during cycling, so I thought I'd get some all-important group think here!

 

[MnFish1]

What did you ever find out? I guess I thought maybe with the fires in your area - the CO2 levels could indeed be higher outside - but I guess that would have to be a fire pretty close to your house
lol