How to Raise pH in Reef Tanks

[Dreamreefcorals]

Great and informative, appreciate the insights!

 

[Freenow54]

I think any ongoing effect of GFO on pH is by encouraging precipitation of calcium carbonate on and downstream of the GFO. It encourages it in a number of ways, including lowered phosphate and organics, acting as a seed crystal, and release of iron which accelerates such precipitation.

Thanks want to follow

 

[TeeJay87]

I do not know if you mentioned this in your first part but I recently discover the worst pH thief in my aquarium - use of GFO!, My pH has normally run between 7.9 ro 8.15 during summertime. And I both add Na2CO3 during night and use outdoor air that pass through a CO2 trap.. Around 1/9 something started to happen - my pH rise up to a swing of 8.15 to 8.25 during the weekend 5 - 8/9 when we was away. I did not understand this. Its also during this time I did my CO2 investigations with sampling each hour. My room CO2 was around 430 - 620 but it did not explain my higher pH.

The 9:th - I calibrate my pH probe and did not have it to start again. I change probe and calibrate it - still high pH but erratic. Decide to recalibrate and when I did that I discover that my GFO reactor had not been started after last time (1/9) I clean it. Took it out - load with around 400 ml new GFO (ATI phosphate stop) Started the filter and finish the calibration - and read 7.82 in the aquarium. Re calibration - still low pH. Now it has slowly rise to the normal swing between 8 and around 8.1. Clean again around 11:30 (local time) but did not change media - and a fast dropp to 7.82 that now around 7 hours later have raised to 8.02. I have filter flush befor my GFO media, hence not so much bacteria growth in the media - it last longer.

As it look for the moment - my GFO lower my pH with around 0.2 units. I will of cause redo the shout off of the media reaktor in order to see whats happen with my pH

dKH has been between 7.1 to 8.6 during this time

Sincerely Lasse

It’s not a sexy answer, but perhaps the GFO is removing enough availability of phosphate and/or trace elements such that growth in the tank is limited when GFO is being used. As Miami Reef pointed out, a tank full of corals and coralline boost pH in 2 ways: removal of CO2 and increased alkalinity demand allowing for increased dosage of pH-enhancing alkalinity supplements. So the hypothesis is that it’s possible removal of GFO increased coral/coralline algae/algae growth, which increased pH.

 

[Lasse]

It’s not a sexy answer, but perhaps the GFO is removing enough availability of phosphate and/or trace elements such that growth in the tank is limited when GFO is being used.

Nope - my PO4 is around 0.3. If it is a true observation I did (and not a lightning strike caused by my electrode) - then it must be a chemical reaction. Its known from other phosphorus-precipitating chemicals containing iron. I have not confirm it yet. I run without GFO at the moment - but when I start again - I will see how my pH react.

Sincerely Lasse

 

[TeeJay87]

Nope - my PO4 is around 0.3. If it is a true observation I did (and not a lightning strike caused by my electrode) - then it must be a chemical reaction. Its known from other phosphorus-precipitating chemicals containing iron. I have not confirm it yet. I run without GFO at the moment - but when I start again - I will see how my pH react.

Sincerely Lasse

What about the removal of trace elements limiting growth in the aquarium? GFO also binds to Copper, Manganese, and Iron among other important trace elements.

 

[Lasse]

I have run without any GFO since the start of this month. I start to use GFO today and the pH drop is there again - not so much because I use lower amount of GFO.

Last week . my scrubber needs to be changed - I will do it later in this week

Sincerely Lasse

 

[Schelly]

Thanks for this awesome write up! Would you mind expanding on why adding fresh water at pH 7 to ocean water at pH 8.2 raises the pH?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for this awesome write up! Would you mind expanding on why adding fresh water at pH 7 to ocean water at pH 8.2 raises the pH?

Miami has passed away, but I can explain that one. This is an example where I beleive the google search ai gets the wrong answer because it does not understand chemistry. It is one of my reef chem questions of the day.

https://www.reef2reef.com/threads/r...he-day-299-new-salt-water-parameters.1019373/
Jumping to the answer:

pH rises a small amount because bicarbonate is a weaker acid as salinity declines. That is, the salts in seawater encourage bicarbonate to come apart into H+ and carbonate. When there are fewer ions present by dilution with the fresh water, fewer bicarbonate ions break into H+ and carbonate, and less H+ means pH is higher.

 

[Schelly]

Thanks for this awesome write up! Would you mind expanding on why adding fresh water at pH 7 to ocean water at pH 8.2 raises the pH?

Miami has passed away, but I can explain that one. This is an example where I beleive the google search ai gets the wrong answer because it does not understand chemistry. It is one of my reef chem questions of the day.

https://www.reef2reef.com/threads/r...he-day-299-new-salt-water-parameters.1019373/
Jumping to the answer:

pH rises a small amount because bicarbonate is a weaker acid as salinity declines. That is, the salts in seawater encourage bicarbonate to come apart into H+ and carbonate. When there are fewer ions present by dilution with the fresh water, fewer bicarbonate ions break into H+ and carbonate, and less H+ means pH is higher.

Thanks so much, this is great. I’m sorry to hear about Miami, I have been looking back at his articles to learn and really appreciate his work.

 

[kharn101]

Great write-up, sorry to also hear about Miami. Do you know if he was using kalk and no calcium reactor?

I have a calcium reactor and kalk. I am having an issue with the kalk being consistent in the batch. Creating some small swings in my alk.

The calcium reactor does keep it pegged (alk), but creates low pH for sure. My pH is low at 7.5 at night. I might have my scrubber stop recirculating. I am also running a drop10 algae scrubber and gfo.

Wondering if I should stop the calcium reactor altogether and use the kalk to raise my all to the 9-10 range. I am in a basement with little to no windows. I might consider running an airtube outside, but it's quite far from a source.

 

[Randy Holmes-Farley Verified Community Expert]

How are you making kalkwasser?

 

[kharn101]

Using BRS, Kalk, 2 tsp per gallon. Mixing this in a one-gallon jug container. I don't clean out the jug that I mix the container with that has the slurry at the bottom? However, don't think that is the issue because there isn't a saturation point for Kalk?