Understood. I would say to work on getting more bubbles.
The pH will reflect the amount of dissolved CO2, so, as your plants use it, the pH will go up. Continuously adding pH at about the same rate as your plants consume it will allow your pH to stabilize.
I'm working on keeping a target pH as well as a target ppm dissolved CO2. I'm not sure if it's possible, but I'm trying!
And, really and truly, people have been amazingly helpful in my thread. I would be nowhere near where I am in terms of understanding if it weren't for the knowledgeable people here.
Finally, water hardness outright baffled me at first. I read over and over and over again how degrees related to parts per million and it just didn't make sense to me how the number of drops of each test could be the number of degrees but different parts per million. I would sit there, staring at that chart, thinking, "I am an educated person. How am I not able to understand these numbers that can hold still in this chart?"
I have two tanks running right now. One is 29 gallons with blue rams, Harlequin rasboras, a dwarf gourami (who is the least compatible with the water conditions, but he's not going anywhere ?), rabbit snails, trapdoor snails, and male guppies. I had been doing nothing to increase hardness, and that's where the CO2 is going. Lots of plants. Our 10 gallon has pregnant female guppies, and nerite and mystery snails. Only a few plants. I kept a hermit crab calcium cake in the tank as well as adding Epsom salt with water changes. Now I have cuttlebones in each tank, but I foresee those dissolving more slowly than the hermit crab cakes.
The 10 gallon consistently has a kH of 9 - 12 and gH between 18 and 20. The pH is usually higher, too- 7.6 to 7.8. Using the equation I posted just a bit ago, dissolved CO2 would tend to hang out around 8ppm. In the 29 gallon, the water is very soft. kH around 4 and gH a bit below 10. The pH had been only slightly lower than the 10 gallon, which, according to that equation, meant that my dissolved CO2 hung out around 2ppm.
The CHART (and its underlying equation) has shortcomings in the aquarium environment where carbonates can be things other than CO2, like CaCO3 (calcium carbonate). The 10 gallon most definitely does not have more dissolved CO2 because I specifically add other carbonates.
Point being that 1. increasing your kH won't necessarily increase dissolved CO2, and 2. you have to consider other carbonates in your tank when deciding how closely the chart will reflect your tank's actual chemical environment. If you add calcium carbonate, sodium bicarbonate, potassium bicarbonate, or potassium carbonate to increase your kH, you are not increasing dissolved CO2.
Some people artificially lower pH to increase the water's ability to absorb CO2, but using methods other than things like driftwood and peat can make the whole situation very difficult to balance.
Bubbles. Lots of bubbles!
