Just got pH probe and ...

[bklynmet]

Just got pH probe hooked up this past Friday and its been calibrated with 7.0 and 10 solutions. The probe is part of the AC Jr. Anyway, its great getting constant reading. Now, Ive know my pH tends to be on the low side but the monitoring is giving me the following - 8.15 during lights on and 7.85 with lights off. dkH is 10. Mg is low at 1200 ppm and I am slowly bringing that up with mag flakes. Ca was measured at 460ppm. I use kalk water for topoff. I use two-part solution for when Ca and Alk dip lower - but it's rare since starting the kalk two months ago.

My question is how concerned should I be about the pH. I know a pH swing is eveitable after lights out.. I have a refugium lit on a reverse cycle. The skimer is on 24/7. Windows are closed now that it's cooler outside and we have the heat on.
I do not know what else I can do to raise it - but the livestock - corals and fish seem unaffected - except for an anchor hammer who has its polyps not fully extended. Im not sure if it is pH ralated or the sixline bothering it.

what do you think?

 

[Boomer]

Stop the two-part, increase the kalk in the top-off and drip it at night only. This will be trial and error to get it where you want it. Watch the Alk, it is Ok to get up to 11, no higher. Watch the Ca++, it is already getting to high. Increase surface turbulence if you can to drive off CO2. Your low pH is due to increased CO2 at night. You pH swing to to large it is .3 pH units. Try to get it half of that or a .1 - .15 unit swing.

 

[NaH2O]

Boomer, when you say "increase the kalk in the top off" what do you mean by that? Add more kalk? I have a similar problem with my pH right now (and always do this time of year) where I am 7.97 at night and 8.15 or so at the end of my photoperiod. My kalk is dosed through my top-off in a kalk reactor. I have even run my skimmer's airline out the window (we have all gas appliances). I have as much surface aggitation as I can have without splashing water (coast to coast overflow and return via sea swirl makes ripples across the surface). Currently, my alk is a little on the low side, which I'm in the process of correcting, but even when my parameters are balanced my pH is like this. Maybe I should not talk so much on the phone , or I need to hold my breath, or a good excuse not to make dinner? I'm going to be recalibrating my pH probe, but it has been pretty accurate with past calibrations. I need to look into getting a Calcium reactor soon, but I'm not wanting to go there because I don't want the pH dropping any lower than it already is.

I guess I'll be tagging along with this thread...

 

[DonW]

I'll throw in another question. Is there a difference in how well different buffers work. I used to have all sorts of ph issues and like magic they went away the same month I installed my current calcium reactor. The only thing changed was I stopped using kalk. We know it wasnt magic, so what happened?

Don

 

[Boomer]

Nikki

Some do not use a saturated solution of kalk, which is 2 tsp / gal. Same question for you do you run the kalk only at night or 24/7. A kalk reactor is thw way to go usually for pH issues.

pH probe calibration ? Who's calibration solutiuon are you using ? Some are way off. Meaning, you coluld be 8.15 night and 8.3 day. I would not worry much about a .15 pH swing that is fine. Part of your low pH is due to your low Alk.

A Comparison of pH Calibration Buffers
http://reefkeeping.com/issues/2005-02/rhf/index.htm

Don

Yes there is a difference. It based on the ratio and types of various buffers that make up the buffer. For example, using straight baking soda will incresae the Alk but may have little effect on the pH. Washing soda by itself will drive them both up. Some are a combination of the two. Some may have other salts like borate. In NSW borate makes up about .15 meq/ l Alk. There are some very expenisve buffers that if you put a fish in a bag and ship him half-way around the world the pH in the bag does not change, even though the fish is pushing out all kinds of CO2 which should kill the pH.

Are you using a dual reactor Don ?

This part only thing changed was I stopped using kalk. I'm not sure here if the two were maybe mixing some how or not. Many that use reactors have to use kalk to keep the pH from falling. The extra OH- form the kalk will help both the pH and Alk. The other thing reactors or kalk is you anre not adding things like sodium, potaasium which are in some buffers


This may help

Hydroxide Addition
For hydroxide addition, the first thing that happens is that bicarbonate is converted into carbonate:
9. HCO3- + OH- ==> CO3--

and the small amount of carbonic acid present is converted into bicarbonate:
10. H2CO3 + OH- ==> HCO3- + H2O

The net effect is that the pH rise that is normally encountered by adding hydroxide to water is reduced. For example, adding 0.5 meq/L of hydroxide to freshwater would drive the pH into the 10’s. In seawater, the pH rises much less, and the conversion of bicarbonate to carbonate is largely responsible.

In this situation, the tank is now deficient in H2CO3 (because the small equilibrium amount of H2CO3 normally present was partially converted to bicarbonate by the OH- addition), and the tank proceeds to absorb CO2 from the air, bringing the pH back down a bit by releasing H+. There are many ways to show these reactions, but the net process involves CO2 from the air becoming carbonic acid, the carbonic acid deprotonating to bicarbonate, and some of the bicarbonate deprotonating to carbonate:

11. CO2 (atmosphere) + H2O ==> H2CO3
12. H2CO3 ==>HCO3- + H+
13. HCO3- ==> CO3-- + H+

Carbonate Addition
The case for carbonate addition is similar to that for hydroxide. In this situation, the pH rises because much of the carbonate combines with H+ to form bicarbonate. This obviously reduces the H+, which results in a higher pH:

14. H+ + CO3-- (added) ==> HCO3-
In this case, the net short-term effect is that carbonate and bicarbonate increase, and the pH rises (from 8.10 to 8.44 in the experiment above). In the long term, the higher pH causes more CO2 to be pulled in from the air, as was the case with hydroxide additions. This limits the pH rise, and further increases the bicarbonate concentration. Still, the end effect is the same as hydroxide addition: the tank experiences an increase in bicarbonate and carbonate, and in pH

Bicarbonate Addition
The addition of bicarbonate as an alkalinity supplement is rather different. In this case, the bicarbonate partially dissociates into carbonate and H+, and the tank experiences an increase in bicarbonate and carbonate, and a drop in pH.:

15. HCO3- ==> H+ + CO3--
Consequently, the immediate effect on pH is for it to drop. The drop is small because not much of the bicarbonate dissociates at normal tank pH, but enough does to drive the pH a bit lower (from 8.10 to 8.06 in the experiment above).
In the long term, however, the effect is different. Since a substantial amount of bicarbonate was added and the pH did not change much, the tank is now overloaded with bicarbonate with respect to what it would normally have in equilibrium with air. Some of the bicarbonate picks up a proton, becomes carbonic acid, and the pH rises as the CO2 is blown off to the atmosphere:

16. HCO3- + H+ ==> H2CO3 ==> CO2 + H2O

In the experiment above, this effect has caused the pH to rise from 8.06 to 8.33. So the long-term effect of bicarbonate addition (as it is for any addition to carbonate alkalinity) is to raise pH even though the short-term effect was to lower it.

For more http://www.advancedaquarist.com/issues/may2002/chem.htm

Something else for you Donny

Your K+ thing

It just it me

Why not just use some buffer for K+ additions like potassium bicarbonate or potassium carbonate, if one feels a need to add K+ ? These were never brought up IIRC. SeaChem Labs "Marine Buffer" has such, not that one should use this.

 

[DonW]

Boomer
No just a single little schuran reactor. I stopped using kalk at the same time I installed the reactor. It seems almost as if the natural media is doing a better job at buffering ph than the soda and kalk ever did.
As far as the k thing goes. I'm dosing 2ml hr of 4tsp K bicarb in 1000ml water. Thats what it takes to keep it right at 380 any less it falls.

Don

 

[NaH2O]

The kalk is being dosed 24/7 via my auto-top off (if it matters, I'm using Warner Marine's Kalk Plus). There is usually only between 5-10 gallons of RO/DI water in my top-off resevoir at any given time (to avoid a potential disaster, as Nikki's Law would guarantee a disaster if I didn't manually fill the resevoir). I do wonder what the difference would be if dosed only at night. I suppose I didn't think that my evaporation would be lower also at night, when my lights and fans are off, so there probably isn't much topping off taking place. However, I'm leary of only having my top-off on after lights out. It would be dosed too quickly? I use the Tunze Osmolator as my auto top-off.

As for calibration solution, I use the Pinpoint brand on my AquaController.

Don, are you using the Schuran media with your reactor?

I still need to go back and read the bold in the reply to Don. Kind of hard to wrap my brain around it with a 5 year old hyped up about going Trick-or-Treating.

 

[Slickdonkey]

Ok a lot of this is over my head but thought I'd point out you should be sure that your Aquacontroller is reading the correct pH. I and others have been having problems with the lab-grade probe reading up to 0.25 units less than a similarly calibrated Pinpoint monitor.

http://www.reefcentral.com/forums/showthread.php?s=&threadid=956861

I once read one of Randy's articles and he said the most common cause of pH problems is a measurement problem.

I have been struggling with my pH; it has been fluctuating between 7.8 and 8.0, which seems a little low to me. However, I'm beginning to believe this is a problem with my Aquacontroller pH probe rather than an actual problem with my tank.

 

[DonW]

Don, are you using the Schuran media with your reactor?

Yes, well sort of. I use Schuran style media. Pretty much what ever I can find at the time I order it. There is Schuran and there are a few copy cat brands.

Don

 

[Boomer]

Don

Ok then that is great for you. Who cares as to why :lol:

On K +

I did not remember if K+ bicarb was brought out. It is not on our RC chem forum, a least I could not find it. It was all K+ chloride . You made me think about this when you asked are buffers different as some buffers use these.

Nikki

Those cal solutions by PinPoint are right on if you look at the article.

Same question again, is your kalk mix sat. @ 2 tsp / gal ?

 

[DonW]

Don

Ok then that is great for you. Who cares as to why :lol:

On K +

I did not remember if K+ bicarb was brought out. It is not on our RC chem forum, a least I could not find it. It was all K+ chloride . You made me think about this when you asked are buffers different as some buffers use these.

Nikki

Those cal solutions by PinPoint are right on if you look at the article.

Same question again, is your kalk mix sat. @ 2 tsp / gal ?

Yes we talked about it since I cant get K+ chloride. The state of WA is afraid we might go aroung giving people leathal injections.

Don

 

[bklynmet]

Boomer - you are correct in that I am only using 1 tsp per gallon. I'll up it to two and get it to topoff only at night. I hope the water fluctuation doesn't affect the skimmer performace in the sump.

Surface is agitated during the day - with the closed loop on. At night, its not so much so I'll attemp that as well by directing the return water a little higher. I'll also stop the two part and keep an eye on alk.

The probe was calibrated with pinpoint 7 and pinpont 10 - both recommended in the article linked above.

 

[NaH2O]

Yes, well sort of. I use Schuran style media. Pretty much what ever I can find at the time I order it. There is Schuran and there are a few copy cat brands.

Don

Thanks, Don. I was just curious more than anything. There are a number of local reefers that are using Gen-X media that reminds me of the Schuran.

Nikki

Those cal solutions by PinPoint are right on if you look at the article.

Same question again, is your kalk mix sat. @ 2 tsp / gal ?

Well, I suppose I am. How's that for an answer ? I evaporate about 2 gallons a day, so I put in 20 tsp of kalk into the reactor and add more in about 10 days. Should I be testing the pH of the kalk reactor? Maybe I'm not using the reactor correctly. I should start paying more attention to how much water I am evaporating, too. I wonder if my top-off amount has changed.

 

[DonW]

Thanks, Don. I was just curious more than anything. There are a number of local reefers that are using Gen-X media that reminds me of the Schuran.



Well, I suppose I am. How's that for an answer ? I evaporate about 2 gallons a day, so I put in 20 tsp of kalk into the reactor and add more in about 10 days. Should I be testing the pH of the kalk reactor? Maybe I'm not using the reactor correctly. I should start paying more attention to how much water I am evaporating, too. I wonder if my top-off amount has changed.

Nikki,
You can run your reactor only at night with your ato. You need a bypass valve on the pump. If you down load the pdf instructions for the deltec kalk reactors there is a pretty good explanation of how to do this. This way your not just doing a full two gallon top off and spiking your ph.

Don

 

[NaH2O]

Thanks, Don. I'll download those instructions, and see if I can find a bypass valve. The only thing is if I'm not evaporating that much at night, then I'll hardly have any kalk dosing at all because the top-off won't be running as much. Does that make sense?

 

[DonW]

Thanks, Don. I'll download those instructions, and see if I can find a bypass valve. The only thing is if I'm not evaporating that much at night, then I'll hardly have any kalk dosing at all because the top-off won't be running as much. Does that make sense?

I get what your thinking. You use a timer so your only topping off at night.

Don

 

[Boomer]

Nikki that pH for sat kalk solution should be at or near 12.5, @ 77F. Near reef temps of 82F it will be a tad less, like 12.3. No, that is not a typo. Kalk is one of those odd duck chemcials where there is more in solution at lower temps, thus a higher pH at lower temps. and a lower pH at higher temps.

You should be able to find a time line. Even if it is 2 hrs before lights out and 2 hrs after lights on.

 

[bklynmet]

Thanks, Don. I'll download those instructions, and see if I can find a bypass valve. The only thing is if I'm not evaporating that much at night, then I'll hardly have any kalk dosing at all because the top-off won't be running as much. Does that make sense?

I adjusted my topoff pump to be on only during nightime hours with my AC Jr last night though a timer will work fine just as well. I get about 1.25 gals evap a day when not in summer and about 2.25 during summer.
I'm concerned about the side effect of skimmer performance being affected since the water level in sump would drop through the day until top-off starts at night. I guess I can have the skimmer in a container with it's output set above the waterline so influences of in-sump water levels are not a factor (per one of Calfo's discussions) - it just adds an additional item in an already clutterd sump.

Boomer, I did notice pH 0.05 higher after adjusting the return pump to agitate the surface. Thanks for that simple suggestion. I have a DIY kalk reactor that I need to put online once I get a pump for it. That would put saturated kalk into the system.
Question - I guess then I'd have to topoff separate from kalk because I wouldn't want too much saturated kalk in the system - correct? Is there an easy way to automate this without getting a separate dosing pump or manually setting opening/closing bypass valves?

 

[DonW]

You want to be careful how you go about using a ato with kalk only at night. If you let the sump go low all day long , when the timer turns on the ato is going to want to fill it back up until the float shuts it off. You want to make sure that its a slow drip process thus the need for a bypass valve if your using a pump for the ato. A bypass valve is nothing more than a t connection and a jg type valve diverting the water back to the ato tank.

Don

 

[Boomer]

As Don has stated you need to be careful. It is all trial and error. Yes you could to-off seperate. I would look to Don for better answers here

And no you do not want to add to much sat kalk, but some use it full strength. It depends on the demand and the evap rate. The easy way is once you get things set up on time vs evap rate, day and night and how that seems to fit in, then start Kalk at say 1 tsp /gal and see what readings you get. Then bump-up the kalk to the next level, guessing maybe 1 1/2 tsp will do it, then the next level. Going beyound 2 tsps / gal will do nothng but cause precip.

Kepp an eye on tank pH, Alk and check the effleunt pH of the kalk reactor. What is the pH of the kalk solution you are using now ?