pH drastically lower in warm weather AC vs winter...how can this be?

[2Wheelsonly]

Winter: pH 8.29/7.9
Spring: pH 8.01/7.67

Nothing changes as far as windows, stay closed all year winter or summer. No insulation changes, heater is electric heat pump, AC is electric (all same unit). When my AC has been running it seems my pH drops overall.

I also could have gotten some beneficial bacteria strand that's eating pH too as my nitrates are very low (usually keep them around 10 but they have been steady at <1 lately). When I had ultra low nutrient tanks I ALWAYS noticed my pH would run way lower than without.

Anyone know where I should look? I don't want my pH dropping to 7.5 like it did last year!

 

[Tahoe61]

If you have a skimmer run the air line outside.

What is the pH at night versus the pH during the day?

 

[2Wheelsonly]

Not concerned with remedies as much as I am the cause. Skimmer line is already outside...

I figure if pH was stable for the last 5 months at 8.2 but then all of a sudden is down to .2 whole points on average then something drastic is causing it. I fought low pH in the past and it was also during summer.

Windows/Doors never open so the Only difference is my AC is running vs the heat. I don’t have gas heat, it’s a heat pump so it runs constantly in the winter vs spring. I thought maybe since it’s running constantly during the winter it’s bringing in more air vs the summer???

I can’t get a solid answer from an AC specialist to verify if that’s the case they all tell me AC units just recirculate air in the home and do not bring fresh from outside.

 

[2Wheelsonly]

So I just ran my co2 meter; in the fish room it's 565ppm. Outside it's 360ppm. That tells me that indoor co2 should not be an issue...I know people who have around 1000ppm but keep pH above 8.0. This is a fairly new double junction apex ph probe and my secondary one that was in the calc reactor is reading my tank water the same. I just re-calibrated and checked it against test solution. My backup API color test kit is spot on with my ph probe.

I know time and time again people say it's either excess co2 or alk. My alk is 8.1

Scratching my head, I don't want to face another drop to sub 7.5 like last summer

 

[Jeepguy242]

Ph probe temp compensation?

Is your tank warmer in the summer

 

[hart24601]

My ph is always drastically lower in summer with the AC on. It’s very easy to tell when the AC starts by looking at apex pH, I made a game of it last summer when I would look back over the week at the pH of the tank and guess what days the temp was high for the AC to be on but it was obvious so not a very good game.

Not exactly sure why, but for my house it’s a drastic drop.

 

[Jeepguy242]

My ph is always drastically lower in summer with the AC on. It’s very easy to tell when the AC starts by looking at apex pH, I made a game of it last summer when I would look back over the week at the pH of the tank and guess what days the temp was high for the AC to be on but it was obvious so not a very good game.

Not exactly sure why, but for my house it’s a drastic drop.

I could play the same game with my heater. It’s gas so it pushes a slight amount of co2 when it turns on

 

[2Wheelsonly]

My ph is always drastically lower in summer with the AC on. It’s very easy to tell when the AC starts by looking at apex pH, I made a game of it last summer when I would look back over the week at the pH of the tank and guess what days the temp was high for the AC to be on but it was obvious so not a very good game.

Not exactly sure why, but for my house it’s a drastic drop.

This is good to know, it's basically what i'm seeing...the next question is why?

I assume you have electric furnace or is it gas? Everything I read mentions it should go lower in the winter; that makes sense if they have a gas furnace or are used to running windows open. For those of us with electric heat/air I can't figure out why ac lowers pH and heating doesn't?

 

[hatfielj]

I’ve noticed the exact same thing the last couple of days but didnt realize it was from running my AC but it absolutely lines up with starting up the AC.
My pH was running 7.9-8.1 all winter and the last several days it has dropped to 7.7-7.9! What gives? Perhaps our awesome chemist Dr Holmes-Farley may know?
@Randy Holmes-Farley

 

[2Wheelsonly]

I am concerned with growth at this point. All summer my frags sat stagnant and did nothing...once winter hit and my pH went to 8.1+ my growth exploded. I am not sure if that was related to pH or not!

 

[paul barker]

I cant tell you how to raise ph I have tryed everything things to air line outside to co2 scrubbers my ph is 8.0 all the time I even put ph up in my tank and the raised everything but my ph

 

[kazikage42]

I'm having the same issue with my ph. Mine was 8-8.2 all winter also and now its 7.9-8.1. Not a huge deal but would like to know the cause also

 

[lambchops]

I've noticed the same thing here. Right when it got warmer my ph were down a little. During the winter it gets pretty cold and the heat swiches from electric to gas but I don't see a difference when it does. I do have a fairly leaky house so I'm wondering if I have better air exchange when it's colder.

 

[Z-man]

Are you adding more fresh makeup water due to evaporation during the time the AC is running versus the time the heat is running? And what is the pH of that fresh water? Not sure this is it, but I know I normally add less when the AC is not working

 

[hart24601]

This is good to know, it's basically what i'm seeing...the next question is why?

I assume you have electric furnace or is it gas? Everything I read mentions it should go lower in the winter; that makes sense if they have a gas furnace or are used to running windows open. For those of us with electric heat/air I can't figure out why ac lowers pH and heating doesn't?

It’s gas furnace. I don’t notice any ph changes with it or at least nothing drastic enough I can really tell. Not like the AC at least.

 

[2Wheelsonly]

Well I started reading up on lots of different discussions about pH drastically lowering during summer. You have a lot of people saying AC should do nothing but yet soooo many people having the same issue. One guy provided 5 years of pH graphs showing 8.2 avg winter months and drops to 7.8 during summer consistently. People say "oh it's because your house is sealed up in the summer" but then they suddenly go MIA when asked why that doesn't affect the winter months when your house is just as sealed up.

It's hard to accept the "scientific answer" when you see with your own eyes a drop in pH. I was wondering alot during the winter if my pH issues would come back this spring and they did!

Now the question, will my corals suffer and growth be shot when going from consistant 8.25+ to 7.7 on a good day. This hobby ticks me off sometimes!

I can't get an HVAC guy to take on the task of getting a fresh air vent installed in my basement. the only way is drilling through sub wall.

 

[hart24601]

I think I asked Randy this question a couple years ago and he said it wasn’t uncommon as most AC recirculate the air. I don’t remember 100% though.

 

[2Wheelsonly]

I think I asked Randy this question a couple years ago and he said it wasn’t uncommon as most AC recirculate the air. I don’t remember 100% though.

That would make sense but it if that was the case then why would pH be much higher in the winter time with the same system recirculating the air? My AC unit is a heat pump, it does the heating and cooling so it's the same unit hot or cold. Technically the winter should be just as harsh on my pH than summer.

 

[hart24601]

I really don’t know. Maybe the AC runs longer or the furnace draws in some outside air? It’s the opposite of what I thought.

That would make sense but it if that was the case then why would pH be much higher in the winter time with the same system recirculating the air? My AC unit is a heat pump, it does the heating and cooling so it's the same unit hot or cold. Technically the winter should be just as harsh on my pH than summer.

 

[Randy Holmes-Farley Verified Community Expert]

So I just ran my co2 meter; in the fish room it's 565ppm. Outside it's 360ppm. That tells me that indoor co2 should not be an issue...I know people who have around 1000ppm but keep pH above 8.0. This is a fairly new double junction apex ph probe and my secondary one that was in the calc reactor is reading my tank water the same. I just re-calibrated and checked it against test solution. My backup API color test kit is spot on with my ph probe.

I know time and time again people say it's either excess co2 or alk. My alk is 8.1

Scratching my head, I don't want to face another drop to sub 7.5 like last summer

Your indoor CO2 will drive the pH down by exactly 0.20 pH units, if the air is equilibrated with it.

I suspect the pH measurement is in error. Problems with pH measured with controllers is second only to conductivity by controllers in terms of user issues with these devices.

Try measuring pH in a cup, then if still low, try aerating the cup with an air stone to observe the pH rise.