Drop in pH

[Shermy]

during a water test this morning we noticed that our pH has droped to 7.8,

Two questions:
1) That is low for a reef tank correct?
2) How do I correct it?

[prow]

Originally Posted by Shermy

during a water test this morning we noticed that our pH has droped to 7.8,

Two questions:
1) That is low for a reef tank correct?

correct

2) How do I correct it?

first we must find the cause. what are teh tanks other parameters like Ca+ and alk levels? what are you dosing? how old is this tank and whats in it?

[Shermy]

temp: 77.9 (Daily range of 77-80 at most)
Salinity:1.024
Ph:7.8 of course
Ammonia: 0
Nitrate:0ppm
Nitrite:0
Phosphates:0
Calcium: 460

Alkalinity:
We were told that because we don't mix our own water we don't need to test for alkalinity so I don't have that reading.

Dosing:
We don't dose, I am researching that today if anyone has in any input on what to dose with, I would love to hear it.

Age of tank: The tank is going on two and a half months.

[prow]

Originally Posted by Shermy

temp: 77.9 (Daily range of 77-80 at most)
Salinity:1.024
Ph:7.8 of course
Ammonia: 0
Nitrate:0ppm
Nitrite:0
Phosphates:0
Calcium: 460

all good, Ca+ is a little high but not bad. 450 is about max i would go.

Alkalinity:
We were told that because we don't mix our own water we don't need to test for alkalinity so I don't have that reading.

What??? ahhh, someone has miss lead you here. so you use the LFS premixed water then. have you tested their water to see what the alk is running? you really need to test it, in both your tank and the premixed salt water from the LFS. its likely adding some carbonate (not bicarb) will bring things in balance, but again lets test it first and see where we are at before dosing anything.

Dosing:
We don't dose, I am researching that today if anyone has in any input on what to dose with, I would love to hear it.

here is a good read for ya Reef Aquarium Water Parameters by Randy Holmes-Farley - Reefkeeping.com
have more specific stuff i will give links after we get a handle on your tank.

Age of tank: The tank is going on two and a half months.

ok, your tank is still going through some changes now, lots of alk will get used during the first few months, compared to a matured tank, esp in the first 6 months.

i bet your alk is low and this has resulted in lower ph's. but before dosing anything test it and see where your tank is at.

[cbrownfish]

Bad advice regarding Alk testing. You MUST know and maintain your alk in a reef tank.

pH typically is at it's lowest point prior to the beginning of the lighting cycle. It is then usually at it's highest reading just prior to the end of the lighting cycle. This has to do with higher levels of CO2 in the system during the night cycle, and lower levels during the daylight period.

Though 7.8 is technically low, the most important thing to minimize is your pH swing. Keeping the swing within .2 is recommended (7.8 low, 8.0 high as an example). In the closed environment of our homes, CO2 is many times higher that it is outdoors. If you simply open a window near your tank, you can impact your pH and watch it rise. My pH is usualy in the 8-8.2 range and I know many that have a successful tank keeping it below 8.

As a helpful solution, you can:

1. Run a frag tank on a reverse daylight schedule.

2. Run a refugium with macro algae or an algae scrubber on a reverse daylight schedule.

3. Drip Kalkwasser or do your dosing of higher pH additives during the night schedule to increase your pH during that time. I recommend doing that via a sloooooow drip so your pH is only impacted slightly. A sudden dose of additives can spike your pH and hurt your corals/fish/inverts.

[Shermy]

I never mentioned this but our pH was at 8.0 before it dropped, but we have also never tested in the morning. Our torch coral was looking PISSED this morning after our sally lightfoot went on a rampage so we did a quick test of everything to make sure there was nothing wacky going on, which is when we noticed the drop. I am thinking that 7.8 is our low and it is at 8.0 in the hotter parts of the day.........

We use the Catalina "natural" saltwater.

Regarding your comment about the open window, the tank is right next to a window that is slightly ajar/close during the night and open during the day. Depending on the heat. Would you recommend keeping the window only closed all the time or only open? We live in an old house without central air, so windows and doors are almost always open.

[prow]

Originally Posted by cbrownfish

Bad advice regarding Alk testing. You MUST know and maintain your alk in a reef tank.

pH typically is at it's lowest point prior to the beginning of the lighting cycle. It is then usually at it's highest reading just prior to the end of the lighting cycle. This has to do with higher levels of CO2 in the system during the night cycle, and lower levels during the daylight period.

Though 7.8 is technically low, the most important thing to minimize is your pH swing. Keeping the swing within .2 is recommended (7.8 low, 8.0 high as an example). In the closed environment of our homes, CO2 is many times higher that it is outdoors. If you simply open a window near your tank, you can impact your pH and watch it rise. My pH is usualy in the 8-8.2 range and I know many that have a successful tank keeping it below 8.

As a helpful solution, you can:

1. Run a frag tank on a reverse daylight schedule.

2. Run a refugium with macro algae or an algae scrubber on a reverse daylight schedule.

3. Drip Kalkwasser or do your dosing of higher pH additives during the night schedule to increase your pH during that time. I recommend doing that via a sloooooow drip so your pH is only impacted slightly. A sudden dose of additives can spike your pH and hurt your corals/fish/inverts.

good advise but i would not start changing anything just yet. we dont know if there is a CO2 issue or not just yet. esp dont start kalk yet, it adds Ca+ aswell as alk and your Ca+ is already on the high side. just test your alk levels and we will go from there.

[prow]

Originally Posted by Shermy

Regarding your comment about the open window, the tank is right next to a window that is slightly ajar/close during the night and open during the day. Depending on the heat. Would you recommend keeping the window only closed all the time or only open? We live in an old house without central air, so windows and doors are almost always open.

older houses are pretty well vented(or not so insulated), most likely your CO2 levels in the house are ok, where do you live? anyway an open window helps with gas exchange(sometimes that reduces atmospheric CO2 levels, if its high that is).

[cbrownfish]

Originally Posted by Shermy

Regarding your comment about the open window, the tank is right next to a window that is slightly ajar/close during the night and open during the day. Depending on the heat. Would you recommend keeping the window only closed all the time or only open? We live in an old house without central air, so windows and doors are almost always open.

I wouldn't shut a window near the tank at night, especially if it is normally open during the day (unless it is unsafe or there is another reason). This could definitely casue a bigger swing. Based on pH swings, the opposite "window" schedule would help balance the pH and keeping it open (or closed) all the time would help minimize the swing (in theory).

As prow suggested, I didn't expect you to suddenly start dripping kalk but I did want to point out that there are ways that more advanced aquarists deal with the issue.

[prow]

i honestly dout you have a CO2 problem. IMO, your ph issue its likey to be related to low alk, nothing more. adding something like seachems reef builder (not buffer) is all i think you will need to do. but still lets find out if your alk is ok, if so, then you might want to think about CO2. cbrownfish is rgiht on the ph, but if you do have a big swing its probably related to low alk. i would only worry about CO2 if all other parameters are good and you still are getting low ph's. a shot in the dark, what we ahve here is a metabolic issue not a respiration issue, JMO.

[Shermy]

I am in San Diego, Inland. Boo! I grew up ON the beach and being 25 min for the past 4 years is something I am still not used to.

Alright, well then, I will be back this afternoon with the results of an Alk test. Thank you all for your help.....being currently jobless is going to give me and our reef tanks some good solid quality time

[cbrownfish]

CO2 is a primary factor that controls pH in our aquariums because of the closed environment. If you live in a home and have people, animals, or other pets producing CO2 (breathing), you have a higher level of CO2 in the environment. Take a glass of your tank water and test the pH. Take that glass of tank water and leave it outside for 1-2 hours and re-test, it will be higher in most cases, even without agitation.

Low alk is a possibility but IME, CO2 is the typical culprit.

[cbrownfish]

Causes of Low pH Problems

As described above, low pH problems are those where the pH is below about 7.8. That is, where the daily pH low drops below 7.8 for any portion of the day. Of course, if the pH reaches a low value of pH 7.9, aquarists may still want to raise it, but the need is not so immediate. Several things can commonly result in low pH, and the solution to each of them is different. Finally, there's nothing to prevent a tank from having all of these problems simultaneously!

The first step in solving a low pH problem is to determine why it exists in the first place. Some possibilities include:

A calcium carbonate/carbon dioxide reactor (CaCO3/CO2 reactor) is in use on the aquarium.

The aquarium has low alkalinity.

The aquarium has more CO2 in it than the surrounding air due to inadequate aeration. Don't be fooled into thinking that an aquarium must have adequate aeration because its water is very turbulent. Equilibrating carbon dioxide is MUCH harder than simply providing adequate oxygen. There would be NO change in the pH between day and night if equilibration of carbon dioxide were perfect. Since most aquaria have lower pH during the night, they also are demonstrating less than complete aeration.

The aquarium has excess CO2 in it because the air in the home that it is being equilibrated with contains excess CO2.

The aquarium is still cycling, and has excess acid being produced from the nitrogen cycle and degradation of organics to CO2.

The Aeration Test

Some of the possibilities listed above require some 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 the pH. Then aerate it for an hour with an airstone using outside air. The pH should rise if the pH is unusually low for the measured alkalinity, as in Figure 3 (if it does not rise, most likely one of the measurements (pH or alkalinity) is in error). Then repeat the same experiment on a new cup of water using inside air. If the pH rises there too, then the aquarium pH will rise with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise inside (or rises very little), then the inside air contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should).


Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com

[prow]

cbrownfish, not sure what leads you to think he has a CO2 issue. in 90% or better of tanks not using a Ca+reactor, CO2 is not an issue. even half of those will not have issues. i agree with what you posted on what CO2 does and what possible causes are if there is a issue with CO2.
everything but;

There would be NO change in the pH between day and night if equilibration of carbon dioxide were perfect. Since most aquaria have lower pH during the night, they also are demonstrating less than complete aeration.

yes CO2 is linked to ph. but, ph is not the measurement of CO2 levels.(wierd, i just posted this on another thread) ph measures what H+ is doing. ph levels are usefull for us in that it allows us to keep an eye on the acidity or alkalinity of the water, not CO2 concentrations. however, CO2 does have a direct impact on H+ concentrations. CO2 in water is shown here; H2O + CO2 = H2CO3 = H+ + HCO3. there are many things that effect H+ activity and thus many things effect the ph (acidity/alkilinty) in our tanks.
swings are more a result of respirations from things like algae, corals, fish, bacteria ect...even phosphates effect CO2 and carbonate levels. HCO3 has jsut as big of impact on ph BTW. photosynthesis has a huge effect because it changes pCO2 levels and that effects H+ shifts and thus ph swings. atmospheric CO2 does little in the way of ph swings in our tanks. it does effect the water-air CO2 flux which impacts pCO2 levels but no so much shifts/swings. even with perfect aeration and "equilibration of carbon dioxide were perfect" there will be still shifts/swings in ph, with living things involved.

low alk will have more of impact on ph swings and in his young tank, if all he has been doing is water changes with NSW, there will not be much Ca+ used up, but alk on the other hand will get used up. as time goes by and a few water changes are done, Ca+/alk will become imbalanced.(high Ca+ with lowered alk). futhermore, to compensate for lower alk levels some sand rock may be dissolved for the alk, this also adds some Ca+, bringing his Ca+ levels above NSW levels like we are seeing here.

As a helpful solution, you can:

1. Run a frag tank on a reverse daylight schedule.

2. Run a refugium with macro algae or an algae scrubber on a reverse daylight schedule.

3. Drip Kalkwasser or do your dosing of higher pH additives during the night schedule to increase your pH during that time. I recommend doing that via a sloooooow drip so your pH is only impacted slightly. A sudden dose of additives can spike your pH and hurt your corals/fish/inverts.

sorry to seem like i am picking on you, i dont mean it like that
i just dont think this is a solution for his issues. good to know though, if he can not keep ph up while all other parameters, esp alk, are with in the norm. otherwise i dont see any reason think excess CO2 would be an issue here. as i pointed out before his tank is new and going through changes so more alk will get used up, with his routines why would you want to advocate adding these things?