PH on the drop - Can't seem to isolate cause, any suggestions?

[brahm]

I'm trying to understand what is going on with my PH as of the last month. Up until this system (past 20+ years ) I arguably ignored PH. It was something I wrote off as not being able to control or accurately monitor so I did neither. However with the advent of tridents handing the big 3, and everything humming along it's afforded me some bandwidth to play with PH.

So here's the scenario.

Where I started.
PH in the Winter was mid 7.8s-8.0
In the Summer/Spring/Fall - with windows open 8-8.3ish - with the swamp cooler running up to 8.5!

Long story short, I got spoiled over summer winter came back ph dropped and I decide it was time to see if I couldn't do something about it.

Where I went

Ran a line for my skimmer outside (Boosted my Ph w/the windows closed from 8-8.2ish
Added a Kalk stirrer, boosted my ph from 8.2-8.4/8.45ish

It was humming along great for the past 6 months or so, and I noticed a huge difference in my animals in the winter they were looking like they did in the summer, with better PE, anemones looked very healthy; not that they looked bad now but really full.

Where I am now. (ignore the 8.06 I was zapping aptasia and it spiked)

As of a month ago, I noticed my PH was creeping up without any changes I figured it was time to calibrate the probe. When I did It dropped, for redundancy's sake, I swapped to a new probe I had stowed away *purchased 6 months ago. At that point, I thought maybe my calibration fluid has gone bad so I purchased a new calibration fluid and a new probe, and it dropped yet again after calibration. I've tried swapping the probes between each other to no avail.

During this time frame outside temps raised and my windows to the house have been open every day; which previously had raised ph. I live in a rural area 400 miles from any city with great air quality.

I have great gas exchange with an absurd amount of surface agitation (nothing has changed in this regard)
My Skimmer is still running outside, I also went through and cleaned it to make sure everything is running as it should; everything checks out.

I tried cleaning out and replacing the Kalk in my Kalk Stirrer. It doesn't seem to want to stay at saturation, however.. I've been adding Kalk by the cup (now up to 3ish), and unless I manually lift and lower the stirrer which is running 24/7 it doesn't seem to agitate it very well, but even without the Kalk reactor I should be at least at 8.0 on the low end as I was prior to adding Kalk.

All other parameters are within expected ranges. The inhabitants all seem fine, I'm not worried about the tank crashing or anything however I can notice a difference in the inhabitants specifically the anenomes they are as "full" as they are when my PH is elevated.

Not sure where to look next. Any suggestions?

 

[EeyoreIsMySpiritAnimal]

How does your tank look? Do any corals seem stressed? If not, don't chase numbers...

 

[brahm]

How does your tank look? Do any corals seem stressed? If not, don't chase numbers...

I hear what you are saying, and that is something I have and do often respond to folks looking for help who are new in the hobby.

However, it's important not to ignore trends in your parameters. For my tank to be running in a specific range for months on end, and then suddenly show a clear pattern of week-over-week decline (change) in those parameters could be a precursor to a future disaster; even if everything looks "fine" now.

Often with healthy inhabits there can be a delayed effect and today's "why did my ph suddenly drop but everything looks fine" can turn out to be tomorrow's "all my parameters are looking good but suddenly my corals started to STN"

There is a difference between chasing parameters and trying to understand why something changed without a clear cause.

 

[carlosec83]

It could be your probe was showing a stable "bad reading"before calibrating when you saw it creaping up, now with new probe and calibration your levels are actually accurate now and have been this way for a while. Just a thought.

 

[laverda]

You stated your other parameters are fine. What are the specifically?

 

[brahm]

It could be your probe was showing a stable "bad reading"before calibrating when you saw it creaping up, now with new probe and calibration your levels are actually accurate now and have been this way for a while. Just a thought.

Possible, however I do calibrate them on a regular basis, the reason this kicked off was I saw an out of the norm pattern of ph rising without a clear cause and calibrated the first probe.

I think it’s a combination of something related to the probe(s) or apex and ???

Yesterday I put my probe in some calibration solution to see if it would match and it was off by .18 in multiple fluids & tests. After two calibration attempts I was able to shore that up to .04. Which some how translates to a .2 bump in the tank (now measuring from 7.95-8.15)

but even with that being on kalkwasser, skimmer plumbed outside, cheato (reverse lighting) extremely high surface agitation older house with all the windows open, etc etc.. I should be in the 8.3ish range. As I Have been under these conditions prior. And I can see in the animals they are not acting as they do when my ph is elevated.

 

[brahm]

You stated your other parameters are fine. What are the specifically?

Salinity 35ppt
Temp ranges from 77-78
Alk 8.5 +/- .2
Magnesium 1450 +/- 30
Calcium 450 +/- 20
Haven’t tested N/P in a while but more than happy to is folks feel that is relevant to ph. Last I checked it was around 5 & .05

Nothing extreme, I’m a middle of the road guy.

 

[Pkunk35]

1st off. Amazing post, love seeing the graphs and very well laid out explanation it helps when trying to think of your problem as you have been…
I’ve been studying a lot on trying to move pH in our reefs. Some thoughts/q’s I had:

Photosynthesis affects pH
1). Do you run chaeto at all?
2). Have you added any inhabitants or do you think your coral have grown a lot?

Alkalinity affects pH
1) has your alk changed at all during this period of observation?

adding kalk affects pH
1) have you changed your kalk consumption?
2) is your method of kalk addition consistent (the kalk stirrer does not sound consistent, I just use a container, add kalk, add RO, shake very hard with lid on for 1 min or less, dose the supernatant liquid till it’s gone)

the probe reading is just wrong
1). I admit, I feared what happened to you happening to me, so I have never calibrated my Apex pH probe lol and looks mostly at the swing. I’ve been thinking about buying a Milwaukee probe.

hope these stimulate some thoughts for ya, let us know what comes of it.

 

[HuduVudu]

@brahm buy a CO2 monitor. Just do it.

When I close my windows at night (2 ppl 1000ft2 apt) my CO2 will shoot up to 1600ppm. Open all windows to get cross breeze in the morning an hour later 500ppm. Then slowly down to near the 400ppm that I see most of the day. I also leave the windows open all day. I have taken to leaving the window open a crack all night and that keeps me at 900ppm. With A/C or heat on 700-800ppm.

I don't normally test for pH. I tested last night for grins at lights out ... 8.1.

I really think know what is going on with your indoor air CO2 is really really really important. Plus the meters are cheap. Mine sits on my desk, so I can watch it all day. The information is very interesting, and helpful.

I don't really think the skimmer outdoor air thing is enough. Maybe with a CO2 absorbing media. Honestly, I think if having my tank low in CO2 is a benefit, then why wouldn't I have my breathing air the same.

My 2 cents.

 

[Pkunk35]

Totally on the meter, I had to buy one during COVID for my shop bc supposedly it can measure when too many people are in a room (or so at least this was suggested to me at the height of COVID)
Using it home (Chicago) has been eye opening in terms of CO2 in the room. Opening a cross draft will indeed push CO2 to near outdoor levels very quickly. Problem is in the winter we seal all the windows with plastic and stay inside all day, pushing CO2 levels way up.

I def miss California and open windows all day…

 

[Macdaddynick1]

Salinity 35ppt
Temp ranges from 77-78
Alk 8.5 +/- .2
Magnesium 1450 +/- 30
Calcium 450 +/- 20
Haven’t tested N/P in a while but more than happy to is folks feel that is relevant to ph. Last I checked it was around 5 & .05

Nothing extreme, I’m a middle of the road guy.

Do you run a calcium reactor?

When was the last time you cleaned your skimmer and the air intake?

P.S. it does look like the probe error. My probes also shift upward when they are on the way out.

 

[brahm]

1st off. Amazing post, love seeing the graphs and very well laid out explanation it helps when trying to think of your problem as you have been…
I’ve been studying a lot on trying to move pH in our reefs. Some thoughts/q’s I had:

Photosynthesis affects pH
1). Do you run chaeto at all?
2). Have you added any inhabitants or do you think your coral have grown a lot?

Alkalinity affects pH
1) has your alk changed at all during this period of observation?

adding kalk affects pH
1) have you changed your kalk consumption?
2) is your method of kalk addition consistent (the kalk stirrer does not sound consistent, I just use a container, add kalk, add RO, shake very hard with lid on for 1 min or less, dose the supernatant liquid till it’s gone)

the probe reading is just wrong
1). I admit, I feared what happened to you happening to me, so I have never calibrated my Apex pH probe lol and looks mostly at the swing. I’ve been thinking about buying a Milwaukee probe.

hope these stimulate some thoughts for ya, let us know what comes of it.

Thanks!!

Photo-
1) - Yes I do have a small amount of cheato running in the sump with a reverse light cycle to my lights. I usually half it once a month, typically two solid handfuls.

2) No, I can't even recall the last time I added a new coral or fish to the tank. The acro's are growing but most things started off as "modern" frags and are now growing to "old school" frags or mini colony size.

Alk -
1) Not out of the norm, it does its typically daily fluctuations but has held within an acceptable range (shooting for an 8.5 average)

Kalk
1) I haven't made any changes to the amount I am dosing, I am feeding the kalk stirrer with a dosing pump so it runs on a set increment of 2700/ml a day.
2) It's hard to say I've only now added a ph probe to the kalk stirrer. It does keep stirrering but if I want it to hold 12.3+ ph in the kalk stirrer I need to swoosh it around manually once a day. I am not sure why this would be something that would only start happening now the kalk stirrer, and the pump running are running as they have been since I installed them. I wish I would have started out with a ph probe installed from the get-go so I can have data to compare to.

Probe
1) I agree something is/was off with the probe. I did calibrate it again it took a few tries but I was able to get it hit 6.96 in 7.0 solution prior it was reading .18 or so off. I am not sure however if it is the probe or the APEX I meant to call Neptune today but didn't have time.

 

[brahm]

@brahm buy a CO2 monitor. Just do it.

When I close my windows at night (2 ppl 1000ft2 apt) my CO2 will shoot up to 1600ppm. Open all windows to get cross breeze in the morning an hour later 500ppm. Then slowly down to near the 400ppm that I see most of the day. I also leave the windows open all day. I have taken to leaving the window open a crack all night and that keeps me at 900ppm. With A/C or heat on 700-800ppm.

I don't normally test for pH. I tested last night for grins at lights out ... 8.1.

I really think know what is going on with your indoor air CO2 is really really really important. Plus the meters are cheap. Mine sits on my desk, so I can watch it all day. The information is very interesting, and helpful.

I don't really think the skimmer outdoor air thing is enough. Maybe with a CO2 absorbing media. Honestly, I think if having my tank low in CO2 is a benefit, then why wouldn't I have my breathing air the same.

My 2 cents.

Any recommendations on a c02 monitor? Everything I saw on amazon either had horrible reviews or was rather pricey?

The main thing that is throwing me off is the change in PH without the change in behavior. When I ran my skimmer line outside my ph raised on average by .2, I did this prior to installing the kalk stirrer, and I did it as a means to combat my venturi getting clogged (which it resolved).

 

[brahm]

Totally on the meter, I had to buy one during COVID for my shop bc supposedly it can measure when too many people are in a room (or so at least this was suggested to me at the height of COVID)
Using it home (Chicago) has been eye opening in terms of CO2 in the room. Opening a cross draft will indeed push CO2 to near outdoor levels very quickly. Problem is in the winter we seal all the windows with plastic and stay inside all day, pushing CO2 levels way up.

I def miss California and open windows all day…

Ya, that's where I am stumped. In Sept/Oct I took the steps needed to have the same ph in the winter as I do when I have all the winters open in the summer, and it worked great for 6 months. Now here I am and despite opening up all the windows again and PH is plummeting...

 

[brahm]

Do you run a calcium reactor?

When was the last time you cleaned your skimmer and the air intake?

P.S. it does look like the probe error. My probes also shift upward when they are on the way out.

I do run a calcium reactor, no change to it in the past 6 months (at which point I cleaned it out, replaced the media, full service). It's running with a duel chamber and a tuned carbon doser that shuts off the C02 (as a failsafe) when it hits the desired levels inside the reactor. I also have it dripping into my fuge. With the addition of Kalk the calcium reactor is running a lot less

Prior to yesterday (as I was thinking the same thing) I fully dismantled and cleaned the reactor a few months ago. Yesterday I did the same but there wasn't much to clean, a couple of strands of cheato, and a sponge. No change in my ph since cleaning it. Anytime I see my PH drop the first thing I check is my venturi but with the combination of running air from the outside, and also I have the skimmer shut off momentarily twice a day I can't remember the last time it clogged.

Probe was my initial thought, I've tried 3 different probes at this point. The 3rd one I was able to calibrate within .04 of 7.0 and as a result, I am now seeing ph up to around 8.13 which is still a far cry from 8.3+ where the animals seem to really thrive.

 

[Macdaddynick1]

I do run a calcium reactor, no change to it in the past 6 months (at which point I cleaned it out, replaced the media, full service). It's running with a duel chamber and a tuned carbon doser that shuts off the C02 (as a failsafe) when it hits the desired levels inside the reactor. I also have it dripping into my fuge. With the addition of Kalk the calcium reactor is running a lot less

Prior to yesterday (as I was thinking the same thing) I fully dismantled and cleaned the reactor a few months ago. Yesterday I did the same but there wasn't much to clean, a couple of strands of cheato, and a sponge. No change in my ph since cleaning it. Anytime I see my PH drop the first thing I check is my venturi but with the combination of running air from the outside, and also I have the skimmer shut off momentarily twice a day I can't remember the last time it clogged.

Probe was my initial thought, I've tried 3 different probes at this point. The 3rd one I was able to calibrate within .04 of 7.0 and as a result, I am now seeing ph up to around 8.13 which is still a far cry from 8.3+ where the animals seem to really thrive.

New probes usually show lower ph for me too, I just accept that as a more accurate number. Try drippring your effluent directly into the skimmer like this for just one week: . Let me know if you see any improvement in ph. (It does not precipitate or clog the pump if you’re worried btw)

Other than that, you can do a few things, 1. get a larger/stronger skimmer.
2. Try to pressurize the calcium reactor, see if that utilizes more co2 ( someone told me that before).
3. Raise your Alk.
4. Increase your sump photoperiod.
5. If you have a 3D printer, there is a way where you can 3d print your Venturi intake to increase the size of the openings for both water and air. I was able to mod my skimmer with a little 3d printed intake, which honestly turned my Skimz into a completely different skimmer. It went from being the worst skimmer I’ve ever used to the best thing that ever happened to my reef. I can change the nozzles to essentially turn my AC skimmer into a DC skimmer by messing with the intake of air to water ratio.

 

[Pkunk35]

I’m sure you have read but maybe not, anyway good for the thread:
Randy Holmes-Farley article “Low pH Causes and Cures

If the probe/readings aren’t a problem and it doesn’t sound like they are, I’m guessing maybe it’s the kalk addition or method that is failing here since it’s mechanically driven and has been setup for a while which always seems to make things fail in efficiency in reefing.

do u use a dosing pump for the kalk stirrer? And when do you dose it, I try to dose the majority of the kalk water at night to counteract the pH plummet of lights out

I thought 3:40 and on was interesting to this conversation. he also talks about probe calibration is prob worth listening to

ACI aquaculture on Kalk

hope these help, it is a bit puzzling…

 

[brahm]

Thanks for the suggestions. The thing that’s throwing me off is I had 6 months of great “in the winter/burning woods, windows closed, multiple probe calibrations” 8.30+ ph.

adding kalk in the evening w/a dos. Windows are now open, fugue is going strong, etc etc it doesn’t add up as to why my ph would now be tanking. Why would what worked for so long stop working?

I’m hesitant to change my cxrx setup as it’s been running for 1.5 years without issue. My alk stability is within .1ish daily swings.

I did add a ph probe to my kalk stirrer an avast marine k2 it seems I am not getting fully saturated kalk. I’ve tried cleaning it and adding fresh kalk and I’ll get a boost for a day or so then it sets in around slightly below 12 and rapidly depletes over the course of the night and bumps back up during the day. If I add a little manual stir help I can get a small temporary bump). I’ve tried adding more kalk (got around 3c in there now) to no avail. The stirrer seems to be moving fine and runs 24/7.

At this point I’m toying with manually mixing up batches of kalk that I run through my dos/stirrer for redundancy vs pulling from my ato reservoir. I am dosing 2700ml a day so a 5 gallon jug should last me around a week.

@Randy Holmes-Farley

 

[Randy Holmes-Farley]

It is easy enough to determine the source of the CO2 causing low pH (high indoor CO2, inadequate aeration with indoor air, or pH measurement issues) by doing this aeration test from the article above:

The Aeration Test

Some of the possibilities listed above require some 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 the pH. Then aerate it for an hour with an airstone using outside air. The pH should rise if the pH is unusually low for the measured alkalinity, as in Figure 3 (if it does not rise, most likely one of the measurements (pH or alkalinity) is in error). Then repeat the same experiment on a new cup of water using inside air. If the pH rises there too, then the aquarium pH will rise with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise inside (or rises very little), then the inside air contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should).

 

[brahm]

It is easy enough to determine the source of the CO2 causing low pH (high indoor CO2, inadequate aeration with indoor air, or pH measurement issues) by doing this aeration test from the article above:

The Aeration Test

Some of the possibilities listed above require some 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 the pH. Then aerate it for an hour with an airstone using outside air. The pH should rise if the pH is unusually low for the measured alkalinity, as in Figure 3 (if it does not rise, most likely one of the measurements (pH or alkalinity) is in error). Then repeat the same experiment on a new cup of water using inside air. If the pH rises there too, then the aquarium pH will rise with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise inside (or rises very little), then the inside air contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should).

Sure, took a little digging but found an airstone and a pump.

I did the tests a little backward but here is what came back.

Test 1) Grabbed a Solo cup of tank water Set it next to the sump in the stand, and put the ph probe in it; got a measurement 7.86 , ran the airstone for about an hour and watched it rise up to 8.1

Test 2) Grabbed second Solo cup of tank water. Took a measurement 7.88 brought it and the airstone outside let it run for about an hour and half (went on a bike ) removed the airstone brought the cup inside placed it understand the and inserted the ph probe into it slowly rose to 8.07.

Note: I did not continue to aerate the water inside the house so the first test was done while under aeration as I could not run the ph probe outside to monitor the cup while being aerated.

So what next? Seems odd that inside air gave me better results than outside but that could be the result of continuing to aertate while testing inside, and not being able to do so outside?

My skimmer is running and I'm getting plenty of wet skimmate (I've cleaned it twice now), my return pump is at a 100% I have a large overflow, I have 4 gyres that I clean every 4-6 weeks pushing massive amounts of water and aerating the tank (See attacted videos)

I did find an issue with my Kalk stirrer that I am unsure at this time what to do about. Last nite I mixed up 5 gallons of kalk in a jug, and moved my dosing pump line from my ATO resevior to the saturated kalk jug. When I woke up, I saw no change in my PH, it actually dropped about the way it typically has been as of late since the issues have started to arise.

However, when I went to check on the jug to see how much it consumed I found it hadn't conusmed barely anything at all. I had accidnetly looped the line out of the water inside the jug. When I noticed the issue I re-ran the line and poof the PH inside the stirrer went up to 12.3 - Which to me means that the low saturation numbers that were coming from the PH of my Kalk stirrer are somewhat accurate.

When I first I got the stirrer while I didn't have probe on it I saw obivous gains from adding Kalk. Now it seems like it's not staying saturted. I've emptied all the Kalk, cleaned everything out, added fresh Kalk. I'm dosing 2800ml a (sorry thought it was 2700ml) on a reverse schedule of my lights.

Which is much less then the Avast Marine K2 is rated for. My stirrer stirs 24/7 and appears to be moving just fine yet isn't saturating as it should.

Any suggestions?

Thanks again!