pH too high

[Miami Reef]

You’ll also save $$ on CO2 media.

Pro tip: maintain alk around 7.0-7.5dKH. It will require less dosing to maintain, and the CO2 aeration effect will equilibrate to lower pH if the alk is lower — both will result in less pH, which is what you need.

 

[gbroadbridge]

Very high pH is a significant risk factor for precipitation. Once you start to have precipitation, the seed crystals will further encourage more precipitation. It will be a domino effect.

To remedy that, you’ll need to switch to sodium bicarbonate. It’s just a headache and not worth risking because then you’ll have to have the opposite result: low pH for a while.

In my opinion, 8.4 is the highest we should be striving for. Any higher, and it causes me to feel angst.

My tank has been running like this for ages.
Soda Ash dosing and CO2 scrubber on the skimmer intake.
Probe is calibrated at pH 7 and 10.
Confirmed with a standalone Milwaukee ph meter.

Doesn't seem to bother anything and I stopped worrying about it.

 

[Miami Reef]

My tank has been running like this for ages.
Soda Ash dosing and CO2 scrubber on the skimmer intake.
Probe is calibrated at pH 7 and 10.
Confirmed with a standalone Milwaukee ph meter.

Doesn't seem to bother anything and I stopped worrying about it.

How high is your alk?

 

[gbroadbridge]

How high is your alk?

Not particularly high ...

 

[Miami Reef]

Not particularly high ...

OK that’s good to know. Your numbers are about where mine are now (my pH goes as high as 8.5 at times). I haven’t had precipitations issues as of yet, but it does worry me when it gets high.

Thanks for the reassurance. Maybe it’s not so much of a risk as I once thought. Seems like a lot of people in this thread are pushing pH up.

 

[butterfield]

You could try alternating between dosing NaOH during the nighttime when pH tends to be lower and soda ash during the daytime when pH tends to be higher. Both could be calibrated to maintain alkalinity during their respective dosing times and pH theoretically would be more stable.

 

[Formulator]

Update - I lowered my target Alk to 9.0 from 9.5 and disconnected my CO2 scrubber. It seems to have been effective at bringing me down just a tad, which is what I wanted.

I’m not willing to cut my Alk back all the way to the 7’s as I’m striving for rapid growth right now after my tank reboot last year.

We will see tonight, but based on my low point this morning I expect to max out below 8.6 tonight.

 

[Miami Reef]

Update - I lowered my target Alk to 9.0 from 9.5 and disconnected my CO2 scrubber. It seems to have been effective at bringing me down just a tad, which is what I wanted.

I’m not willing to cut my Alk back all the way to the 7’s as I’m striving for rapid growth right now after my tank reboot last year.

We will see tonight, but based on my low point this morning I expect to max out below 8.6 tonight.

We have the same goals. :)

 

[scotty333]

Not particularly high ...

What are you using of reef factory to get that Ph graph?

 

[Formulator]

Update: So far it seems like I might have found a sweet spot, maxing out my pH at just a tad over 8.6 at the end of the photoperiod. To summarize for others in the future looking to do the same - I achieved a pH reduction of about 0.5 units by removing my CO2 scrubber and lowering my Alk target from 9.5 dKh to 9.0 dKh.

Again, striving for rapid growth I want to maximize pH for those benefits while ensuring I don’t have water clarity and equipment issues due to abiotic CaCO3 precipitation. I think this is that sweet spot based on the last 2 days and my tank’s appearance.

 

[Gordon Schumway]

Very high pH is a significant risk factor for precipitation. Once you start to have precipitation, the seed crystals will further encourage more precipitation. It will be a domino effect.

To remedy that, you’ll need to switch to sodium bicarbonate. It’s just a headache and not worth risking because then you’ll have to have the opposite result: low pH for a while.

In my opinion, 8.4 is the highest we should be striving for. Any higher, and it causes me to feel angst.

Im having the same issue and was looking to switch from sodium carbonate to bicarb. No matter the time of day, my ph reads above 8.6. Would i still be dosing the same amount? Is there anything else i need to consider when doing this?

 

[gbroadbridge]

Im having the same issue and was looking to switch from sodium carbonate to bicarb. No matter the time of day, my ph reads above 8.6. Would i still be dosing the same amount? Is there anything else i need to consider when doing this?

If you are reading over 8.6 all day most likely you have a measurement error.

Have you tried an aeration test?

 

[Miami Reef]

Im having the same issue and was looking to switch from sodium carbonate to bicarb. No matter the time of day, my ph reads above 8.6. Would i still be dosing the same amount? Is there anything else i need to consider when doing this?

It’s most likely test error. Sodium carbonate cannot get you consistently over 8.6 unless there was a massive overdose.

 

[Randy Holmes-Farley Verified Community Expert]

Im having the same issue and was looking to switch from sodium carbonate to bicarb. No matter the time of day, my ph reads above 8.6. Would i still be dosing the same amount? Is there anything else i need to consider when doing this?

Highly unlikely that is accurate, and if it is, simple aeration will lower it.

 

[Gordon Schumway]

Highly unlikely that is accurate, and if it is, simple aeration will lower it.

Well thats why im confused. Every test kit i try says 8.6+. I test other water samples (my salt mix, my brothers tank, my friends tank) none say 8.6. As far as aeration, are you talking surface agitation? Protein skimmer? I have a 75 gallon tank with a 20 gallon sump plumbed into the basement which has a reefocto regal 150 running 24/7 and 3 powerheads aimed up making the surface very turbulent

 

[Randy Holmes-Farley Verified Community Expert]

Well thats why im confused. Every test kit i try says 8.6+. I test other water samples (my salt mix, my brothers tank, my friends tank) none say 8.6. As far as aeration, are you talking surface agitation? Protein skimmer? I have a 75 gallon tank with a 20 gallon sump plumbed into the basement which has a reefocto regal 150 running 24/7 and 3 powerheads aimed up making the surface very turbulent

Any type of aeration will bring it down unless alkalintiy is super high. Skimmer and tank top water movement both do it.

You could also try this aeration test using inside air. If it does not drop considerably, it is not accurate. if it does, then you know aeration is needed.

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.

 

[Gordon Schumway]

Any type of aeration will bring it down unless alkalintiy is super high. Skimmer and tank top water movement both do it.

You could also try this aeration test using inside air. If it does not drop considerably, it is not accurate. if it does, then you know aeration is needed.

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.

I have done that test on my tap water (for fresh tanks) to see if it was really as low as 6.5, so i am familiar with that. Made no difference on my reef tank test. And as i stated before, every single test kit used said 8.6+, and every water sample ive tested that is not my tank, all read between 7.8 - 8.3. So if my skimmer is running 24/7 and if I turn up the powerheads anymore, i will be blasting water out of the tank. Its very turbulent. Idk what else there is to do. I was watching marc levensons live stream a few weeks ago and asked him this very question about switching to bicarb. He said yes it would be a good possibility that could work. I noticed someone on this thread mentioned it, so im just looking for more info on it. Im not a chemistry major by any means, but it seemed like there may some merit to this. Combined with other info ive found and my previous job sending me to chemistry seminars. Its to my understand sodium carbonate raises ph and alk, while bicarb only raises alk with little effect on ph. And if the ph is really 8.6, it would not be as difficult for the coral to get rid of the extra hydrogen, as the hydrogen is already lower. Compare to the amount of hydrogen in, lets say 7.8. But again, im not an expert and im just looking for more info

 

[Randy Holmes-Farley Verified Community Expert]

I don’t understand. Did you try the aeration test in a cup of water?

 

[Gordon Schumway]

I don’t understand. Did you try the aeration test in a cup of water?

Yes. I have tried everything everyone has suggested, twice. Ive never had this problem and my tank has been going over 10 years. The only thing ive changed in the last 5 years is swapping out an old powerhead with an mp40. This is why i joined here. I have exhausted every avenue ive tried, except switching to bicarb. Which is what i remember from my old job. If ph is high, but alk is low. Use bicarb. If you need to raise both, use soda ash. Im trying not to compair apples to oranges. As this is for pools and hot tubs. You also dont keep your pools ph that high, those are 7.4 - 7.6, which is based on our (human) ph, but the basic principle seems to be there. I was just looking to see if the same holds true for reef tanks? I added bicarb on my last supply order so well see what happens

 

[gbroadbridge]

Yes. I have tried everything everyone has suggested, twice. Ive never had this problem and my tank has been going over 10 years. The only thing ive changed in the last 5 years is swapping out an old powerhead with an mp40. This is why i joined here. I have exhausted every avenue ive tried, except switching to bicarb. Which is what i remember from my old job. If ph is high, but alk is low. Use bicarb. If you need to raise both, use soda ash. Im trying not to compair apples to oranges. As this is for pools and hot tubs. You also dont keep your pools ph that high, those are 7.4 - 7.6, which is based on our (human) ph, but the basic principle seems to be there. I was just looking to see if the same holds true for reef tanks? I added bicarb on my last supply order so well see what happens

Soda Ash does indeed raise pH, but the effect is temporary.

I'm not sure exactly why you are concerned, most likely the reading is incorrect.
Are you seeing any symptoms of distress in the tank occupants?

If not, I'll really wouldn't worry about it - chasing numbers is pointless.

My tank peaks at about 8.8 some days and I just ignore it.
Next week it may peak at only 8.4.