pH dropping with unknown influence

[GothFishKeeper]

last month I moved my tank to the basement, and therefore my ph dropped as it wasn’t next to an open window the whole time anymore, so I finally went ahead and installed the CO2 scrubber that I’ve had lying around for a year. It worked for about a week, giving between 8.1-8.2, and then dropped back down to the 7.9s again. I’m very confused as to why because I’m using the BRS color changing media and it didn’t change color to indicate that it was used up.

Next I tried running airline tubing from the venturi to the outdoors through the fire escape window, as seen in this picture:

The tube goes through the screen, out the top of the escape, and is hung over a low branch on the bush on the side of the house. It has a mesh bag over the end of it to keep bugs out.
This did absolutely nothing for my ph.

I’m at a loss, because despite having a 30g refugium in a second sump for this 90g tank, my ph is still pretty much at the minimum. Here’s the graph from my hydros system along with pics of the sumps (I changed my filter socks right after taking these pics lol).

Any advice or suggestions on what to do would be greatly appreciated, thanks!

 

[Randy Holmes-Farley]

I’m not sure you need to do anything as all pH values shown on the graph are acceptable, but doing this aeration test can help diagnose the source of the CO2 that is lowering the pH.

pH and the Reef Aquarium - REEFEDITION

by Randy Holmes-Farley For many aquarists, pH is not something that they have much experience with aside from their aquarium. For many, pH is almost a black box measurement: something to be considered, but whose physical meaning makes little sense to them. This article will Read more here...

www.reefedition.com

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.

 

[ShanePike]

Any idea why the graph is so choppy? Is it possible your pH probe is going bad? That's what my graph looked like for a few weeks before the probe crapped out completely.

Just for comparison, here's my pH graph:

 

[Randy Holmes-Farley]

Any idea why the graph is so choppy? Is it possible your pH probe is going bad? That's what my graph looked like for a few weeks before the probe crapped out completely.

Just for comparison, here's my pH graph:

It looks normal. pH always rises during the light cycle due to photosynthesis consuming CO2 and drops at night as respiration produces CO2.

pH is determined mathematically by alkalinity and CO2. :)

 

[ShanePike]

It looks normal. pH always rises during the light cycle due to photosynthesis consuming CO2 and drops at night as respiration produces CO2.

Oh yeah I know that, but look at his graphs compared with mine. My pH rises smoothly and falls smoothly. His generally rises and falls, but has extraordinary fluctuation as it's doing it.

To show you what I mean, here is the Apex graph from my other tank when my probe was starting to fail:

And here's what it looks like with a good probe:

And his should look even smoother than my original one because he's looking at a longer time period. Look at my Hydros graph and his over the same time period:

Mine looks like how pH should rise and fall, right?

 

[Randy Holmes-Farley]

Ok, I thought you were asking about your graph.

He has noise on the order of 0.04 pH units. I would not take that as a sign of a probe problem.

 

[Ol’Murph]

last month I moved my tank to the basement, and therefore my ph dropped as it wasn’t next to an open window the whole time anymore, so I finally went ahead and installed the CO2 scrubber that I’ve had lying around for a year. It worked for about a week, giving between 8.1-8.2, and then dropped back down to the 7.9s again. I’m very confused as to why because I’m using the BRS color changing media and it didn’t change color to indicate that it was used up.

Next I tried running airline tubing from the venturi to the outdoors through the fire escape window, as seen in this picture:

The tube goes through the screen, out the top of the escape, and is hung over a low branch on the bush on the side of the house. It has a mesh bag over the end of it to keep bugs out.
This did absolutely nothing for my ph.

I’m at a loss, because despite having a 30g refugium in a second sump for this 90g tank, my ph is still pretty much at the minimum. Here’s the graph from my hydros system along with pics of the sumps (I changed my filter socks right after taking these pics lol).

Any advice or suggestions on what to do would be greatly appreciated, thanks!

The color changing media you are using doesn’t change to a deep purple color. It is a very subtle change…. so subtle in fact only half of the media actually changes and that is only visible once you remove the cartridge from the housing.

I get about a week or so out one cartridge full of media, then I change it out. If we have company for the weekend, it may last 5 or so days. If we go away for a weekend, it lasts 10 to 12 days. I gauge when to replace based on my ph dropping. First 24 to 48 hours, the ph will rise to 8.25 to 8.27, then over the course of the week, will slowly drop down to about 8. Once it gets between 8 and 7.95, I replace the media.

If you wanted to increase that interval, you could go to the jumbo size reactor or even go larger, but either the amount of media used is about the same.

 

[GothFishKeeper]

First off I wanna apologize to everyone in here for the delay in response. I did read everything as it was being posted though and I have some updates…

The color changing media you are using doesn’t change to a deep purple color. It is a very subtle change…. so subtle in fact only half of the media actually changes and that is only visible once you remove the cartridge from the housing.

I get about a week or so out one cartridge full of media, then I change it out. If we have company for the weekend, it may last 5 or so days. If we go away for a weekend, it lasts 10 to 12 days. I gauge when to replace based on my ph dropping. First 24 to 48 hours, the ph will rise to 8.25 to 8.27, then over the course of the week, will slowly drop down to about 8. Once it gets between 8 and 7.95, I replace the media.

If you wanted to increase that interval, you could go to the jumbo size reactor or even go larger, but either the amount of media used is about the same.

Thank you so much for the input on this, I did change out the media and it did in fact bump it up. Not a huge amount, but a sufficient amount. The media was still completely white even looking at it out of the reactor, so I would’ve never realized that was an issue before reading this.

Oh yeah I know that, but look at his graphs compared with mine. My pH rises smoothly and falls smoothly. His generally rises and falls, but has extraordinary fluctuation as it's doing it.

To show you what I mean, here is the Apex graph from my other tank when my probe was starting to fail:

And here's what it looks like with a good probe:

And his should look even smoother than my original one because he's looking at a longer time period. Look at my Hydros graph and his over the same time period:

Mine looks like how pH should rise and fall, right?

I’m unsure if my probe is failing, but I do have something that might suggest it maybe is being influenced by something, the refugium light.

When I orginally setup my hydros controller with the ph probe, I put it at the very end of the second sump that is a multiple stage 30g refugium, right next to the hob overflow that leads right back to the chamber on my main sump where it originally gets pumped into the fuge from. The location of the probe is circled in this picture:

However for the last few weeks, I’ve had it in the return chamber of the main sump. I moved it because there was sponge growing on the end of the probe. This did not however change anything regarding the readings, as far as I know, even though I removed the sponge.

Fast forward to last night: I added an additional light to the refugium, one identical to the much more intense light of the two I had on there originally. I did this in hopes of increasing the rate of photosynthesis of the chaeto in the first two chambers, and the gracilaria in the third.

Within an hour of this light being added, the readings of my ph almost completely stabilized, only wavering by 0.01 when the refugium lights turned off, and then back up when the ramp up on my radions progressed. The pattern can be seen in this image:

I am unsure if the light is somehow influencing a false ph reading though, because it seems very unusual for it to stabilize so intensely at such a rapid rate. Please correct me if I’m wrong on that though, I hope I am.


Also, I just did a little experiment. I am not home right now to see it happening in front of me, but I wirelessly turned on the refugium light again and it bumped up. Very slightly, but it’s still a bump up.

Everyone please let me know your thoughts on all of this, thanks!

 

[ShanePike]

I'm not sure what's going on, but that's definitely the smoothness that you should see in your pH graph. Lights can definitely have an effect, so maybe you're on to something!

 

[Randy Holmes-Farley]

Both through air and in water types of interference are known problems for pH meters. Any sudden jump is interference of some sort unless you added something near the probe.

Moving cords away from each other, using a battery powered pH meter, and taking the pH in a cup away from the tank can all help these issues.

 

[GothFishKeeper]

Both through air and in water types of interference are known problems for pH meters. Any sudden jump is interference of some sort unless you added something near the probe.

Moving cords away from each other, using a battery powered pH meter, and taking the pH in a cup away from the tank can all help these issues.

I wouldn’t necessarily call this a sudden jump though, right? It’s now still following the pattern of the last couple days, but i just find it odd that a single light can make something so stable all of a sudden. It just feels too good to be true.

 

[Randy Holmes-Farley]

I wouldn’t necessarily call this a sudden jump though, right? It’s now still following the pattern of the last couple days, but i just find it odd that a single light can make something so stable all of a sudden. It just feels too good to be true.

Turn the light on and off manually and look for a sudden change. Lack of a sudden change means it’s not likely from the light unless it is simply driving photosynthesis.

 

[GothFishKeeper]

I wouldn’t necessarily call this a sudden jump though, right? It’s now still following the pattern of the last couple days, but i just find it odd that a single light can make something so stable all of a sudden. It just feels too good to be true.

Turn the light on and off manually and look for a sudden change. Lack of a sudden change means it’s not likely from the light unless it is simply driving photosynthesis.

Will do for sure, im working a double today so won’t be home for another couple hours still but I’ll keep everyone updated

 

[GothFishKeeper]

Will do for sure, im working a double today so won’t be home for another couple hours still but I’ll keep everyone updated

Tested it out when i got home and the only change that happened was a 0.01 difference after about a minute of hitting the on/off button

 

[UncommonSense]

Tested it out when i got home and the only change that happened was a 0.01 difference after about a minute of hitting the on/off button

Try a 30-60min manual cycle for the refugium lighting; photosynthesis, and water mixing takes a bit!

 

[Randy Holmes-Farley]

Are we just talking about ordinary photosynthesis in a refugium? That will certainly raise pH.