Journal Joel Armstrong - My journey

Thought I'd check a another degassed sample of tank water. Left a sample out for 3 days, and reading is at 7.95 pH.

I also looked at KH with a salifert test. Same as I've tested before, which is around 3 dKH.

What I find strange is the pH reading, isn't 7.95 pH very high if KH is around 3 ?

With CO2 on, tank gets down to 6.15-6.20 pH. Assuming readings are correct, that's too high of a pH drop, correct?

I've calibrated my pH pen several times, and get the same readings, even replaced the probe to double check again, and I still get the same readings.

Since I'm using tap water, could it be that there's something added to my tap water causing pH to be this high?, I don't know..

I find myself questioning everything lately..
 
SkaleyAquatics said:
interesting. could temperature of the water be playing a role? have you happened to check what the degassed samples temp is. what is the temperature of your tank?
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Yes I have actually.. it's summer here so tank water is around 24 - 24.5 °C. Sample left outside, similar temp when tested.
 
Joel Armstrong said:
What I find strange is the pH reading, isn't 7.95 pH very high if KH is around 3 ?
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I have a similar thing in Journal - 1000 Gallon High Tech Planted Tank where my degassed pH is around 7.8 despite having 2 - 2.5 KH. I have also dropped my pH to a similar target without problems. Though my tank fully degasses by the next morning. Do some carbonate sources just raise the pH more than others while contributing the same amount of KH? I believe my tanks KH source is from the concrete rock.
 
Joel Armstrong said:
What I find strange is the pH reading, isn't 7.95 pH very high if KH is around 3 ?
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Seems normal to me.

KH 2 (i.e. 44 ppm HCO3) = pH ~7.8

Under normal circumstances, the pH follows the bicarbonate (= HCO3) content. This means that low bicarbonate content = low pH, and conversely high bicarbonate content = high pH. However, even with zero bicarbonate content the pH will be around ~5.5, and even with extremely high bicarbonate content the pH will not exceed 8. 3. In other words, until some other factors come into play (e.g. nitrification, or strong acid/base or CO2 addition ... forming weak carbonic acid), the pH in our aquariums can only range between 5.5 and 8.3. So if you want a pH of, say, 6.5, you must not have more than 5 ppm HCO3 in the water (i.e. KH = 0.2). How to achieve this? Aquarists usually use three methods: they remove bicarbonates in hard tap water either by (1) reverse osmosis or (2) adding a strong acid - e.g. HCl. Or (3) they "get around" the problem of high pH by adding CO2, and the higher their initial pH, the more CO2 they have to add to bring the pH down to the desired level.
 
Marcel G said:
Seems normal to me.

KH 2 (i.e. 44 ppm HCO3) = pH ~7.8

Under normal circumstances, the pH follows the bicarbonate (= HCO3) content. This means that low bicarbonate content = low pH, and conversely high bicarbonate content = high pH. However, even with zero bicarbonate content the pH will be around ~5.5, and even with extremely high bicarbonate content the pH will not exceed 8. 3. In other words, until some other factors come into play (e.g. nitrification, or strong acid/base or CO2 addition ... forming weak carbonic acid), the pH in our aquariums can only range between 5.5 and 8.3. So if you want a pH of, say, 6.5, you must not have more than 5 ppm HCO3 in the water (i.e. KH = 0.2). How to achieve this? Aquarists usually use three methods: they remove bicarbonates in hard tap water either by (1) reverse osmosis or (2) adding a strong acid - e.g. HCl. Or (3) they "get around" the problem of high pH by adding CO2, and the higher their initial pH, the more CO2 they have to add to bring the pH down to the desired level.
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Is this for water at equilibrium with atmospheric CO2, 420 ppm?

Could you cite the source of calculation method @Marcel G?
 
Yugang said:
Is this for water at equilibrium with atmospheric CO2, 420 ppm?
Could you cite the source of calculation method ... ?
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I used the open source software PhreeqcI for the calculation and verified it by practical measurements.

PS: Please keep in mind that this data is only valid for clean (dead) water. In "live" aquarium water other factors come into play (mainly plants, fish and microbes with their metabolites) which can then shift the pH up or down, sometimes quite significantly. For example, in one aquarium where my pH was 5.5 to start with, I now have a pH of ~3.
 
Marcel G said:
I used the open source software PhreeqcI for the calculation and verified it by practical measurements.

PS: Please keep in mind that this data is only valid for clean (dead) water. In "live" aquarium water other factors come into play (mainly plants, fish and microbes with their metabolites) which can then shift the pH up or down, sometimes quite significantly. For example, in one aquarium where my pH was 5.5 to start with, I now have a pH of ~3.
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Does it include the correct equilibrium with atmospheric CO2, ie 420 ppm? This would be the correct reference for our case, and is obviously different from a situation with no, or lower free CO2 gas.
 
Yugang said:
Does it include the correct equilibrium with atmospheric CO2, ie 420 ppm?
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I'm no expert on the program. But I have consulted it with an expert who uses it to teach hydrogeologists. After his revision, I use the following input data:

phreeqci.png
The "Equilibrium_phases" line is set to equilibrium with atmospheric CO2. I don't know if this is correct (the professor advised me to do it this way).

When you run the program with this input, it will show you two states: one before the equilibrium and one after => see the output. The average aquarist will probably get a headache out of this though, because all the concentrations are in moles, whereas we are used to ppm. So, for example, 1,622e-04 M HCO3 = 0.0001622 M = 0.1622 mM = 9.9 ppm HCO3 (0.1622 M * 61.0168 g/mol HCO3).

Among other things, you can find out what kinds of compounds you get when you add various chemicals (in my case I think it was NH4NO3, H3PO4, K2CO3, CaCO3, K2SO4, MgSO4, MgCl2, CaSO4, CaCl2 and some micros) and which ones stay dissolved vs. which ones precipitate out (and in what amounts). This can be read from the "Saturation indices" section at the end of the output file. All compounds with a negative value will remain dissolved in the water, whereas all compounds with a positive value will precipitate out. [So you can see, for example, that some iron in the form of Fe(OH)3, FeOOH and Fe2O3 precipitated out of my water, and manganese was similarly affected.] It's probably good to take this with a grain of salt though, because (as I mentioned) all of these outputs are only valid in pure/dead water).

PS: Sorry, Joe, for the off-topic post.
 
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thank you @Marcel G

@Joel Armstrong agree, something seems unusual to me with your pH reading. I am no expert though.
What you may try if you like to double check is use distilled water, baking soda to 2 KH. I’d expect your ambient equilibrium pH reading at least half a point lower than what you are measuring now.
 
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20241201_155700.jpg

Some crazy looking tips.. not sure what's up 🤔

If anything, I thought I may be using too much CO2, but are these funky looking tips a sign of too little CO2?

I've been getting a higher than expected degassed pH reading lately, so I'm unsure about CO2 levels.

I've been dosing 22.5 - 7.5 - 30 between 50% water changes. Half at water change, and then the half split into two doses throughout the week.
 
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I don't like to get into discussions about CO2 because the prevailing opinion is that the more CO2 the better. From my point of view, if you have CO2 around 10 ppm, plants cannot suffer from a lack of it in any case (and under any circumstances). However, as far as I know, CO2 acts a bit like a drug, and plants can adapt to its concentration very quickly (but only in one way, i.e. from low to high), and a problem can arise when their initially high CO2 concentration drops, causing something like "withdrawal". While I don't have as much experience as other aquarists here, if I were you, I would think about whether your aquarium is experiencing significant pH fluctuations, i.e. whether the pH is significantly lower during the day than at night. I can pretty well imagine that if you have a pH of around 6 during the day and it rises above 7 at night, that could have a negative effect on many of the more sensitive (acid loving) plants.
 
Marcel G said:
if I were you, I would think about whether your aquarium is experiencing significant pH fluctuations, i.e. whether the pH is significantly lower during the day than at night. I can pretty well imagine that if you have a pH of around 6 during the day and it rises above 7 at night, that could have a negative effect on many of the more sensitive (acid loving) plants.
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Well, pH is around 6 during the day, and does rise to about 7.2 overnight.

I have two species of plants that are growing weird.. ludwigia super red and the myriophyllum roraima..

Thanks for responding.
 
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