PH of 6.4 with a KH of 4 should tell me that there is enough CO2
That doesn't tell you anything. You need to look at the CO2 concentration profile at regular intervals from gas on to lights off. Only then can you see how the gas is behaving.
If your filter is powerful enough, then you don't need spraybars or powerheads. I advocate the use of spraybars only because it's the
easiest path of ensuring good distribution of flow. There are more aesthetic alternatives, such as lily pipes and so forth, and they work well if they are executed properly to ensure good flow/distribution.
I mean, one can also experience failure while using spraybars if they are placed/oriented improperly or if the flow energy is too low, so I have a standard placement/orientation scheme to minimize or eliminate errors when using the bars, and we suggest to use them
in conjunction with the 10X filter turnover rule.
Again, it doesn't mean that you
have to do it this way, or that doing it another way will always fail. It's just a simple standard technique that works in most cases. All the science has been worked out already for you, just as with the dosing scheme. So you don't have to be Albert Einstein to figure any of this out. Just follow the basic schemes and tweak from there.
One also has to look at the manner in which the gas is being dissolved, as well as the injection rate and the injection timing. So there are a lot of other factors to consider.
What you want to avoid is to be considerate of factors that are either irrelevant, or which only have a negligble effect. pH/GH/KH are three of those types of negligible factors. People waste a lot of time and energy trying to micromanage these parameters, under the Matrix induce illusion that they are super important, but, as it turns out, none of those efforts have any palpable effect. In fooling around with the parameters they may stumble upon something that has a positive effect, but that's just luck. The vast majority of plants have a wide variety of conditions that they can tolerate, so it's useless to focus on these miniscule factors while ignoring the larger and more important fundamentals that affect plant growth.
For carpet type plants, getting CO2 and flow to the substrate is critical. These small plants do not typically live deep under water in nature.They are normally marginal plants (by "marginal" I mean at the margin of the land and water) Many of these plants are not typically found fully submerged, so because of that they usually have easy access to CO2, and as a result, they have not learned how to become efficient at CO2 uptake while under water. So when you dump them 60cm under water and throw gobs of megawatt radiation at them, they fail due to poor gas exchange ability.
So if you follow the same misguided procedure, such as thinking that the plants need lots of light, while being oblivious to their real needs, such as gas exchange enhancement, then odds are that you will continue to experience failure with those species.
Here is a general clue:
When a species of plant is labeled as being "difficult" it's ALWAYS because the plant lacks the talent to uptake CO2 efficiently while being submerged. It's
never ever because the plant requires megawatts of light.
Cheers,
