PH is never right...why? and does it matter?

[nobody]

ok so with both two different test kits and a monitor my ph is always low. I checked the calibration of the monitor and its perfect. Yesterday it was at 8.00 and got to 7.75-7.80 at night. My alk is maintained between 8-11. So whats the deal? does it matter? should i even worry?

[ckusnierek]

Ph will rise and fall as the light go on and off. 8.0 is a lil low. but I would not worry...

[nobody]

Ph will rise and fall as the light go on and off

i understand this just added it for conversation sake. But why would my ph be that low when my alk is where it should be if not higher. I cant dose for ph because it will sky rocket my alk. i did this before with out realizing it.

[crvz]

you're pH is low because you live in Pennsylvania and it's cold, and I'm sure you closed up the house. The CO2 concentration is probably twice what it is outside, and that increased CO2 drives the pH lower in your tank. Does it matter? Probably not at all. Mine is in the same range at this time of year, and it hasnt affected me so far. What could you do to fix it? Draw air for the skimmer from outside or stop breathing.

[luvmylo]

Originally Posted by crvz

you're pH is low because you live in Pennsylvania and it's cold, and I'm sure you closed up the house. The CO2 concentration is probably twice what it is outside, and that increased CO2 drives the pH lower in your tank. Does it matter? Probably not at all. Mine is in the same range at this time of year, and it hasnt affected me so far. What could you do to fix it? Draw air for the skimmer from outside or stop breathing.

@ stop breathing

[wolfe4372]

Originally Posted by crvz

you're pH is low because you live in Pennsylvania and it's cold, and I'm sure you closed up the house. The CO2 concentration is probably twice what it is outside, and that increased CO2 drives the pH lower in your tank. Does it matter? Probably not at all. Mine is in the same range at this time of year, and it hasnt affected me so far. What could you do to fix it? Draw air for the skimmer from outside or stop breathing.

you answered my problem from a few days ago!! yay!

[YLChik]

it will also drop if you have a room full of people

[wolfe4372]

this is a very interesting thread

[tdwyatt]

The issue becomes that your tank begins to act as an accumulating sink for CO2, and may just be an issue with high atmospheric CO2 in your home due to being closed up as already mentioned above for the Pa. winter. If you have adequate alkalinity, and your pH probe has passed the borax test (so we make sure that the issue is not a measurement error it the probe, and this can occur even with a calibrated probe, do the borax test), the accumulation of CO2 has a measurable effect, as shown in the chart below. It may require that you run a hose outside and place a filter tip on it to bring in outside air to your skimmer for low CO2 air intake for your foam. Many threads here on the filter tip, and easy to make device with GAC in it and some filter floss or polyester fiberfill.

Below is a chart for the CO2 concentration determination based on what the actual measured pH via probe of the water column is and the corresponding alkalinity:


Ratio pCO2 For ASW compared to NSW
VALUE IN CHART IS COMPARED TO A VALUE OF 1 FOR nsw AT SEALEVEL, OR x:1

Total Alkalinity (AT)
(mEq/l) . . . 2.0 .. 2.5 .. 2.6 .. 3.0 .. 3.5 .. 4.0 .. 4.5 .. 5.0 ... 5.5 ... 6.0
(dKH) . . . . 5.6 .. 7.0 .. 7.3 .. 8.4 .. 9.8 . 11.2 . 12.4 . 14.0 . 15.4 . 16.8
pH __________________________________________________ _________
7.7---------3.0 .. 3.7 .. 3.9 .. 4.5 .. 5.3 .. 6.0 .. 6.8 ... 7.5 ... 8.3 ... 9.1
7.8---------2.3 .. 2.9 .. 3.0 .. 3.5 .. 4.1 .. 4.7 .. 5.3 ... 5.8 ... 6.4 ... 7.O
7.9---------1.8 .. 2.2 .. 2.3 .. 2.7 .. 3.1 .. 3.6 .. 4.0 ... 4.5 ... 5.0 ... 5.4
8.0---------1.3 .. 1.7 .. 1.8 .. 2.0 .. 2.4 .. 2.7 .. 3.1 ... 3.4 ... 3.8 ... 4.1
8.1---------1.0 .. 1.3 .. 1.3 .. 1.6 .. 1.8 .. 2.1 .. 2.3 ... 2.6 ... 2.9 ... 3.1
8.2---------0.8 .. 1.0 .. 1.0 .. 1.2 .. 1.4 .. 1.7 .. 1.8 ... 2.0 ... 2.2 ... 2.4
8.3---------0.6 .. 0.7 .. 0.7 .. 0.7 .. 1.0 .. 1.2 .. 1.3 ... 1.5 ... 1.6 ... 1.8
8.4---------0.4 .. 0.5 .. 0.5 .. O.6 .. 0.7 .. 0.9 .. 1.0 ... 1.1 ... 1.2 ... 1.3
8.5---------0.3 .. O.4 .. 0.4 .. 0.5 .. 0.5 .. 0.6 .. 0.7 ... 0.8 ... 0.9 ... 0.9
8.6---------0.2 .. 0.3 .. 0.3 .. 0.3 .. 0.4 .. 0.4 .. 0.5 ... 0.6 ... 0.6 ... 0.7
__________________________________________________ _________

Once the total alkalinity and pH are known, the ratio between the partial pressure of CO2 due to the atmosphere on seawater and the actual dissolved C02 of the system being evaluated can be determined utilizing the above chart. With the value from the chart known, you can decide whether you need to start ventilating the tank with outside air to your skimmer (or fans to the surface or remove glass tops) to degas the CO2 content or if you need to increase your alkalinity.

For example, if your system's pH is 7.8 and your alkalinity was 2.6 mEq (7.3 dKH mEq), then the value from the chart for the amount of CO2 dissolved in the water at normal atmospheric conditions is 3.0, so your pCO2 for the tank would be 3 times what it should be for normal concentrations of CO2 in your tank due to atmospheric dissolution of CO2 in the water COMPARED TO NSW (REMEMBER, many of us run higher that NSW values for Ca and alkalinity). If later in this same tank our pH were to be 8.2 but our akalinity were 2.6 mEq (7.3 dKH mEq/l), we would know that our pH was just about right and the amount of dissolved CO2 in the water column (pCO2) would be appropriate for the conditions present in the system.


If our chart lists a value of 3.0, or 3 times the amount of dissolved CO2 in our tank water compared to NSW, we would need to make arrangements to degas the tank for CO2 (and check our delivery rate of CO2 for tanks equipped with CO2-based Ca reactors). For Tanks with CO2 reactors, if they are using a pH controller, we would prolly need to first check the calibration of the controller probe AND the tank probe, then test a second time for alkalinity.


HTH, you can take a maon jar and fill it half way with the tank water, shake it vigorously, allow the jar to remain open for 30 min or so and repeat the process once or twice, then test it again with a probe for pH vaues. Often in systems where the pH is low due to CO2 accumulations, this procedure will allow enough
CO2 to degass to significantly raise the pH of the sample.


HTH

[YLChik]

Originally Posted by tdwyatt

HTH, you can take a maon jar and fill it half way with the tank water, shake it vigorously, allow the jar to remain open for 30 min or so and repeat the process once or twice, then test it again with a probe for pH vaues. Often in systems where the pH is low due to CO2 accumulations, this procedure will allow enough
CO2 to degass to significantly raise the pH of the sample.


HTH

I was actually amazed when I did that when I posted a question like this... I really suggest doing it.

[wolfe4372]

my tank is 12 gallons, i could just turn on my heat and open the window for a few hours.

[DarthOcellaris]

put some house plants in the room to try and offset the c02

[crvz]

Originally Posted by DarthOcellaris

put some house plants in the room to try and offset the c02

How effective is that? It's hard for me to think that it would help to a measurable difference. I'd almost be more inclined to do reverse photoperiod in a sump, either with algae or maybe some frags.

[nobody]

um......ok well i tried to stop breathing but all that happen was i took a nap.........i can run the skimmer venturi line to the window if i needed to. and yes our apartment is closed up and we do not have any plants in the room let alone the apartment. mostly because our dog/cats would eat them. my ph was much better in the warmer months when the windows were open. my ph is about 8.0 durning the day and my alk is 8.5 before i dosed last night. so according to that chart im at 2.4. is this bad?

[DarthOcellaris]

Originally Posted by crvz

How effective is that? It's hard for me to think that it would help to a measurable difference. I'd almost be more inclined to do reverse photoperiod in a sump, either with algae or maybe some frags.

plants use c02 to breath. they expel o2.