pH

FrankSWood · Jul 13, 2019

pH in my 210 gallon reef tank is 7.66, dKH is 13.5. All other measures are within normal range. What is the best way to raise pH gradually to 8.0+

road_runner · Jul 13, 2019

FrankSWood said:
pH in my 210 gallon reef tank is 7.66, dKH is 13.5. All other measures are within normal range. What is the best way to raise pH gradually to 8.0+

Are you sure your ph meaustment is accurate? How are you measuring?
On such high alk I would expect ph is high..

dwest · Jul 13, 2019

How (what test kit or meter) and what time if day did you measure pH? My pH fluctuates about 0.3 pH units during the day. Currently it ranges from 7.9-8.2.

I personally would control the alkalinity where I wanted and let the pH be whatever it is.

FrankSWood · Jul 13, 2019

Ohashimz said:
Are you sure your ph meaustment is accurate? How are you measuring?
On such high alk I would expect ph is high..

Calibrated Apex probe

road_runner · Jul 13, 2019

FrankSWood said:
Calibrated Apex probe

What time?
Ph swing during 24 hours, it peak at your photo period peak.
Mine as an example swing between 8.2 to 7.8 during 24 hours...
Its just so hard to believe on such high alk levels you have low ph.
Any chance you can correlate ph using another test kit or prob? I do not trust apex probs as much especially if they are more than 8-12 months old..

Randy Holmes-Farley · Jul 13, 2019

I’m also not a fan of pH measured by controllers

FrankSWood · Jul 13, 2019

dwest said:
How (what test kit or meter) and what time if day did you measure pH? My pH fluctuates about 0.3 pH units during the day. Currently it ranges from 7.9-8.2.

I personally would control the alkalinity where I wanted and let the pH be whatever it is.

I measured it with the Apex probe and the Salifert test kit. I also have a Hanna pH tester that settled at 8.13. I measured it several times today. Failed to mention that I have lights off to help control outbreak of green hair algae. This is the first time I have been responsible for balancing chemistry - my tech in northern VA set up my aquarium with constant water change. It continues to be a real learning experience.

road_runner · Jul 13, 2019

FrankSWood said:
I measured it with the Apex probe and the Salifert test kit. I also have a Hanna pH tester that settled at 8.13. I measured it several times today. Failed to mention that I have lights off to help control outbreak of green hair algae. This is the first time I have been responsible for balancing chemistry - my tech in northern VA set up my aquarium with constant water change. It continues to be a real learning experience.

Ok so 8.1 is not bad at all. Lowest will be at night..
Are you trying to get it higher than 8.1, or are you trying to fix low point at night?

FrankSWood · Jul 14, 2019

Ohashimz said:
Ok so 8.1 is not bad at all. Lowest will be at night..
Are you trying to get it higher than 8.1, or are you trying to fix low point at night?

I'd be happy w/ 8.1 but which do I trust, 8.1 or 7.6 - both Apex and Salifert indicate closer to 7.6.

road_runner · Jul 14, 2019

FrankSWood said:
I'd be happy w/ 8.1 but which do I trust, 8.1 or 7.6 - both Apex and Salifert indicate closer to 7.6.

Sorry look like sm confused.
Which instrument is giving what result?

Randy Holmes-Farley · Jul 14, 2019

FrankSWood said:
I'd be happy w/ 8.1 but which do I trust, 8.1 or 7.6 - both Apex and Salifert indicate closer to 7.6.

It's always hard to tell which disagreeing tests may be accurate, but one way to help is to do the aeration tests described below and see how much the pH rises when aerated with outdoor air:

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.