Why is my pH 8.6+

[Fazio92]

Hey Everyone,

 

So for the past few days i had ran out of CO2 for my CaRx. Since then my pH has been around 8.4-8.6 consistently! I have not dosed anything, haven't put Kalk in my top off since the move, i recently replaced and re-calibrated my pH probes, so what gives? The only thing that i am thinking of at the moment is that i am having a significant amount of evaporation do to the large surface area of the 300gal rubbermaid, but its being topped off with fresh RO/DI (no kalk) and its in my basement where there is no "fresh" air. So there theoretically there should be a larger value of CO2 vs. O2 in the air; which should diffuse through the water and lower the pH. I'm a little stumped right now, any help would be greatly appreciated, as my CO2 is now running around 20hrs/day. FYI my salinity is 1.025-26.

 

-Anthony

[Supernova26]

Hey man I was in the same boat until I increased the CO2 bubble rate on the calcium reactor. My co2 was running about 20hrs per day and PH was up at 8.6. Now that it runs less but PH is 8.4. Check this out.

 

http://www.thereeftank.com/forums/f67/calcium-reactor-question-tdwyatt-20300.html

[Origami]

Anthony, are you sure that you're measurement tool is calibrated accurately?

 

You might be surprised at how fresh the air is in our basements. If it's used less by people, it's probably more "fresh" than many other living spaces. Also, alkalinity factors into your pH, so a system with high alk will have higher pH numbers for a given CO2 concentration.

[Fazio92]

Hey man I was in the same boat until I increased the CO2 bubble rate on the calcium reactor. My co2 was running about 20hrs per day and PH was up at 8.6. Now that it runs less but PH is 8.4. Check this out.

 

http://www.thereeftank.com/forums/f67/calcium-reactor-question-tdwyatt-20300.html

 

 

So what did you end up doing?

[Supernova26]

I assumed that my tank did not have enough calcium consumption due to the size of the frags, and the fact that I moved everything to a new tank. With nothing being established and no coralline algae the reactor was an overkill. I increased the bubble rate a bit and I ran the reactor every other day for a while and the PH came back down slowly. It's stable now at 8.40 during the day.

[Fazio92]

So after a few weeks of not running the CaRx and doing multiple water changes, my pH still consistently rises to around 8.6. I have also re-calibrated all my probes and changed some out for the 4th time, so my pH is that high. What gives, any help would be greatly appreciated as this has really taken a significant toll on my inhabitants. The only thing that i am thinking that is different from before i moved is the fact that it's in a basement and in a 300gal rubbermaid. Thoughts??? I'm at the point to get rid of everything and start over, but i'm not sure that its not the environment where the tank is. So, if i setup a display not 20 feet from the tub, will i have the same result even with new rock, sand, etc...? I really want a display like i use to have, but i need to fix the problem before setting up a permanent tank, otherwise there is no point moving forward. If anyone would like to stop by and take a first hand look (Reston) to see if i'm missing something, feel free and send me a pm.

 

 

-Anthony

[TonyInVa]

I have been having the same problem. my guess is that its because we are keeping the windows open more often. When it got colder and we closed them it was normal again. Now that it warmed up a little the last couple of days we have opened them back up.

[Fazio92]

I have been having the same problem. my guess is that its because we are keeping the windows open more often. When it got colder and we closed them it was normal again. Now that it warmed up a little the last couple of days we have opened them back up.

 

 

I never keep my windows open, so theoretically i should have a low pH. I didn't even hook up my beckett style skimmer which had the air intake plumbed outside, to help increase the pH.

[Buucca]

You don't mention if the water in the Rubbermaid tub is being aerated. I had an incident where my Ph was creeping up so I recalibrated the meter as you did. It just didn't make any sense so I used a dip test strip and that showed normal range. My reagent had obviously expired and gave me false recalibrations.

[Fazio92]

You don't mention if the water in the Rubbermaid tub is being aerated. I had an incident where my Ph was creeping up so I recalibrated the meter as you did. It just didn't make any sense so I used a dip test strip and that showed normal range. My reagent had obviously expired and gave me false recalibrations.

 

 

I do have aeration not only from the skimmer, but two aerators rated for 125gal, and an MP40 & MP60 at the surface. i guess i should get new reagent, but i know something is still off since all my SPS and clams died and everything else looks ok, definitely not happy though.

[overklok]

Anthony what is your alkalinity? Seems to me you could be on the very high end of the scale.

Check out this http://www.advancedaquarist.com/2002/5/chemistry

[davelin315]

Anthony, I doubt it's the tub, last summer when I kept it outside with fish it didn't rise very high despite being outside and the tubs I have on my system don't keep the pH high and I have to supplement to bring the pH up and run an airline from outside. That said, I suppose it's possible, but I've seen so many of these in action and have used so many of them in the past without any issues that I'm wondering if it's something else. If it is the tub, I feel terrible that I lent it to you...

 

I think I have a Hannah pH checker that I've never opened, if I do, you're welcome to try it on your pH to see if it's just a test kit issue.

 

Which brand of salt are you using, by the way? Perhaps it's something to do with that?

[Origami]

You might be surprised at how fresh the air is in our basements. If it's used less by people, it's probably more "fresh" than many other living spaces. Also, alkalinity factors into your pH, so a system with high alk will have higher pH numbers for a given CO2 concentration.

What's your alkalinity?

[Fazio92]

Anthony, I doubt it's the tub, last summer when I kept it outside with fish it didn't rise very high despite being outside and the tubs I have on my system don't keep the pH high and I have to supplement to bring the pH up and run an airline from outside. That said, I suppose it's possible, but I've seen so many of these in action and have used so many of them in the past without any issues that I'm wondering if it's something else. If it is the tub, I feel terrible that I lent it to you...

 

I think I have a Hannah pH checker that I've never opened, if I do, you're welcome to try it on your pH to see if it's just a test kit issue.

 

Which brand of salt are you using, by the way? Perhaps it's something to do with that?

 

 

Dave, I 100% agree with you. These are the most common large frag setup containers and have proven no problems. I was just going through process of elimination of new things i changed from my new setup. I am just using pH probes through the Apex to test the pH. I am about to go retest the Alk, as i do remember it being high a few weeks ago, but so was Ca and Mg.

 

-Anthony

[Fazio92]

What's your alkalinity?

 

 

Test Results:

 

Alk - 9.6

Ca - 500

Mg - 1275

Cu - 0

N03 - 0

pH - 8.24 (10:30am) (but will typically hit 8.54 by 4pm)

[Origami]

Interesting. 9.6 dKH isn't that high. I'm assuming that your salinity is at around 35 ppt, right?

 

I graphed some equations a while back, based on some technical journal articles that I'd read relating CO2, pH and alkalinity. To do so, I had to assume that a reference point, provided (I think) by RHF in a couple of hobbyist's articles (beginning with this one) that he'd written, were accurate. While I'm not 100% sure that the reference point was accurate, the series of graphs gave a good qualitative sense of how pH and CO2 were related given alkalinity. The graph that I created is reproduced below.

 

 

If I consider the numbers that you've provided, your morning CO2 is around 550 ppm, which is above the average outside CO2 concentration today. Not unusual. The extremely high pH later in the day indicates a CO2 level much lower than outside ambient air. If correct, then in this case, aeration would actually serve to lower your pH. Have you tried measuring the pH of a water sample after it's been thoroughly aerated using fresh air (from outside)?

 

Are you dosing an alkalinity supplement of any sort during the day?

[Fazio92]

Interesting. 9.6 dKH isn't that high. I'm assuming that your salinity is at around 35 ppt, right?

 

I graphed some equations a while back, based on some technical journal articles that I'd read relating CO2, pH and alkalinity. To do so, I had to assume that a reference point, provided (I think) by RHF in a couple of hobbyist's articles (beginning with this one) that he'd written, were accurate. While I'm not 100% sure that the reference point was accurate, the series of graphs gave a good qualitative sense of how pH and CO2 were related given alkalinity. The graph that I created is reproduced below.

 

 

If I consider the numbers that you've provided, your morning CO2 is around 550 ppm, which is above the average outside CO2 concentration today. Not unusual. The extremely high pH later in the day indicates a CO2 level much lower than outside ambient air. If correct, then in this case, aeration would actually serve to lower your pH. Have you tried measuring the pH of a water sample after it's been thoroughly aerated using fresh air (from outside)?

 

Are you dosing an alkalinity supplement of any sort during the day?

 

 

Haven't dosed a single thing in over 2 months. I ran the intake to my skimmer outside one day last week, but no noticeable change in pH (constantly read through the Apex). You are correct, 35 ppt for my salinity. I really don't want to have to constantly run CO2 to maintain my parameters, as there should be a better alternative.

 

-Anthony

[Origami]

I really don't want to have to constantly run CO2 to maintain my parameters, as there should be a better alternative.

You shouldn't have to. It seems unreasonable.

 

This guy had similar symptoms in his tank. In both cases, it traced to bad measurements. However, you've calibrated your probes multiple times (with, I assume, fresh quality calibration solutions).

 

Try aerating a sample of tank water outside with an air pump and stone. Run it for 15 minutes and test it with your pH probe, allowing the probe to settle for at least 5 minutes.

 

Out of curiosity, have you checked your pH against a regular, chemical-type test rather than your probe? Or taken some other, independent measurement?

[Coral Hind]

If the Alk test is not accurate he could have a higher value which is causing the high pH.

[Origami]

If the Alk test is not accurate he could have a higher value which is causing the high pH.

Good point.

[Fazio92]

You shouldn't have to. It seems unreasonable.

 

This guy had similar symptoms in his tank. In both cases, it traced to bad measurements. However, you've calibrated your probes multiple times (with, I assume, fresh quality calibration solutions).

 

Try aerating a sample of tank water outside with an air pump and stone. Run it for 15 minutes and test it with your pH probe, allowing the probe to settle for at least 5 minutes.

 

Out of curiosity, have you checked your pH against a regular, chemical-type test rather than your probe? Or taken some other, independent measurement?

 

 

I haven't tried a chemical test, but yes my reagents should be good and are high quality. Again, something is off even if pH was reading inaccurately because everything went and is completely downhill. I will aerate it outside and let you know what happens.

 

If the Alk test is not accurate he could have a higher value which is causing the high pH.

 

 

About a month ago when this all started my Alk was about 12dKh if i remember (Ca and Mg were also high). That's why i cut off the CaRx about a month ago.

 

-Anhtony

[Origami]

Anthony, what are you using to measure alk? Are you convinced that you're getting a good measurement?

[Fazio92]

Anthony, what are you using to measure alk? Are you convinced that you're getting a good measurement?

 

I'm using a Salifert kit.

[Fazio92]

Ok, just let a cup of water aerate outside for about an hour. Took the pH probe directly out of the tank and within 2 seconds of placing it in the cup of exterior water it dropped from a reading of in-tank 8.43 to a reading of exterior water 8.26. So, what should i do as i am assuming there is a greater amount of CO2 outside then in my house?

 

pH in tank - 8.43

pH in exterior water - 8.26

[Origami]

Right now, the assumption is that there's more CO2 outside than is built up in your tank water.

 

Thanks for the water sample. I'll test it tonight after I get home.