Issue with PH readings & low Alk

Reefer1978 · Mar 27, 2018

This is going to be a bit of a long post, but I do need some help and appreciate any assistance. I recently upgraded my Apex to 2016. With Apex Classic, my daily PH swing was 8.05-8.25, which I thought was great. My skimmer takes oxygen input from outside of the house, which helps keep it stable. As soon I connected 2016, my Ph reading went to 7.8. At the moment, my daily swing is 7.77 - 8.0. Thinking this is odd, I re-callibrated the Ph Probe, but the reading on the apex didn't change at all.

At the same time, I tried to switch my CalRX reactor to higher flow / higher Ph, in low 7s. I am still having a very hard time getting the CalRX to stabilize, and as a result, Alk dropped to 6, and I am dosing daily to compensate.

I also ordered one of the cheappo Ph pens off of amazon to try and re-confirm my readings. Well that was junk and went straight back to Amazon. My tap water read at 5.

So questions that I at the moment:
1. How can I confirm my Ph readings? What's a good pen, or a good, accurate testkit that gets into decimals?
2. Can Apex show an incorrect reading even though callibration readings were decent?
3. Thinking of adding Kalkwasser to my ATO, but it's a nice clean setup. Will it muddy it up?

It's possible my Ph is low due to Co2 in the house. I opened the windows for half an hour last weekend - no impact what so ever. And as I mentioned, skimmer is pulling the air from the outside. What else could it be?

@Randy Holmes-Farley would you have any other suggestions of what to try? I am running out of ideas.

Randy Holmes-Farley · Mar 27, 2018

Reefer1978 said:
This is going to be a bit of a long post, but I do need some help and appreciate any assistance. I recently upgraded my Apex to 2016. With Apex Classic, my daily PH swing was 8.05-8.25, which I thought was great. My skimmer takes oxygen input from outside of the house, which helps keep it stable. As soon I connected 2016, my Ph reading went to 7.8. At the moment, my daily swing is 7.77 - 8.0. Thinking this is odd, I re-callibrated the Ph Probe, but the reading on the apex didn't change at all.

At the same time, I tried to switch my CalRX reactor to higher flow / higher Ph, in low 7s. I am still having a very hard time getting the CalRX to stabilize, and as a result, Alk dropped to 6, and I am dosing daily to compensate.

I also ordered one of the cheappo Ph pens off of amazon to try and re-confirm my readings. Well that was junk and went straight back to Amazon. My tap water read at 5.

So questions that I at the moment:
1. How can I confirm my Ph readings? What's a good pen, or a good, accurate testkit that gets into decimals?
2. Can Apex show an incorrect reading even though callibration readings were decent?
3. Thinking of adding Kalkwasser to my ATO, but it's a nice clean setup. Will it muddy it up?

It's possible my Ph is low due to Co2 in the house. I opened the windows for half an hour last weekend - no impact what so ever. And as I mentioned, skimmer is pulling the air from the outside. What else could it be?

@Randy Holmes-Farley would you have any other suggestions of what to try? I am running out of ideas.

First, the pH range is still OK (whether real now or before). Many people have pH measurement issues with the APEX, for reasons that I do not fully understand, but may in part be related to temperature corrections. The temp probe needs to be in the calibration fluids if the fluids are not at tank temp. You can try the aeration tests below to see if it helps, and if not (using outside air), the measurement may be inaccurate. Does the APEX now read the calibration fluids correctly? Going back and checking is a good protocol.

Higher flow and higher pH in a CaCO3/CO2 reactor may be counter productive with respect to tank pH. Lower flow and lower pH is likely to be more efficient use of the CO2, all of which ultimately gets added to the tank. Think of it this way, it takes a certain amount of CO2 to drop the pH to the point where any significant amount of media begins to dissolve. The more water that you have to drive down to that ph point, the more CO2 is "wasted". Lower flow can also allow more time for the same amount of CO2 added to the water to dissolve media (which can be important if the effluent is not actually saturated for the amount of CO2 added).

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

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.

Reefer1978 · Mar 27, 2018

Randy Holmes-Farley said:
First, the pH range is still OK (whether real now or before). Many people have pH measurement issues with the APEX, for reasons that I do not fully understand, but may in part be related to temperature corrections. The temp probe needs to be in the calibration fluids if the fluids are not at tank temp. You can try the aeration tests below to see if it helps, and if not (using outside air), the measurement may be inaccurate. Does the APEX now read the calibration fluids correctly? Going back and checking is a good protocol.

Higher flow and higher pH in a CaCO3/CO2 reactor may be counter productive with respect to tank pH. Lower flow and lower pH is likely to be more efficient use of the CO2, all of which ultimately gets added to the tank. Think of it this way, it takes a certain amount of CO2 to drop the pH to the point where any significant amount of media begins to dissolve. The more water that you have to drive down to that ph point, the more CO2 is "wasted". Lower flow can also allow more time for the same amount of CO2 added to the water to dissolve media (which can be important if the effluent is not actually saturated for the amount of CO2 added).

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

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.

Thank you Randy. I fully agree with you on the reactor, it's just that I haven't been able to stabilize the flow through it for 8 months now. Looking into a peristaltic pump now as everything else seems to be failing and I am already working on moving it into lower flow/lower Ph.

Since I do not currently trust my Probe readings, do you have a suggestion on a test kit or a specific pen which is accurate as much as possible? My outside air is indeed very different, 40 degrees vs. 78 for the tank. I am also ordering more calibration packets to work on the re-calibration of the probes.

Thank you for the help as always!!!

Randy Holmes-Farley · Mar 27, 2018

Ah, I didn't make the connection to the earlier threads on flow control.

I don't have a specific pH meter I like, but as long as it has two (or more) point calibration it should be OK.

I really am surprised at how many pH "issues" seem related to controller programming complexities.

Reefer1978 · Mar 27, 2018

I did purchase a 2-point calibration pen - it failed miserably. I think it was just a very cheaply made product.

Reefer1978 · Mar 29, 2018

A few updates on this thread if anyone's following with a similar issue:

1. I re-calibrated both Ph probes. This time followed Apex directions to the dot, packets were left floating in the water while the probes were in them (IRWIN to the rescue). Tank and CalRX readings got a little more accurate, less swing, tank Ph is a bit higher now, bottom point is 7.82.

2. I ordered Hanna PH meter just to have a second point of reference, and added comfort level. Looking forward to cross-referencing it against Apex readings.

3. Lucked out and won a Watson Marlow 520U on fleebay, this will be fun and hopefully will get a nice decent flow going that I don't have to re-adjust constantly.

4. My CalRx currently is dripping into the tank, and had a Ph reading of 6.85. Lowering it to 6.75 - right away I see an impact on tank Ph. Tank reached a new low point of 7.8 overnight. @Randy Holmes-Farley, I know you mentioned it before - sealed home, too much co2. But I always figured since I have fresh air going into the skimmer, I am all good. Guess it's still not enough, I can only imagine what my tank would be like without fresh air intake.

Randy Holmes-Farley · Mar 30, 2018

Thanks for the update.

The tank top aeration and the reactor may both be fighting against the skimmer aeration to keep the pH on the lower side.

Reefer1978 · Mar 31, 2018

Hi @Randy Holmes-Farley - Hope you can give me some scientistic feedback. The Watson Marlow 520U came in, and its AWESOME. I was a little surprised how big it was, but it's whisper quiet, I can run it off of my nightstand and I won't hear it. The pump had Marprene® Thermoplastic Elastomer Tubing -- 902.0032.016 tubing, filled with some kinds of a chemical, can't tell from the smell, seems a little oily to the touch. I don't want to risk it and re-use this tubing, but replacement is $125 per roll. Do you think I can get away with ordinary silicone tubing as replacement?

Randy Holmes-Farley · Mar 31, 2018

Reefer1978 said:
Hi @Randy Holmes-Farley - Hope you can give me some scientistic feedback. The Watson Marlow 520U came in, and its AWESOME. I was a little surprised how big it was, but it's whisper quiet, I can run it off of my nightstand and I won't hear it. The pump had Marprene® Thermoplastic Elastomer Tubing -- 902.0032.016 tubing, filled with some kinds of a chemical, can't tell from the smell, seems a little oily to the touch. I don't want to risk it and re-use this tubing, but replacement is $125 per roll. Do you think I can get away with ordinary silicone tubing as replacement?

I'd be concerned that silicone tubing not thick walled enough or designed for constant abrasion might have issues.