speaking of misting, would you mind sharing your thoughts on misting vs reacting?
i was discussing it with a fellow NJAGC member the other day, as he uses a reactor, and doesnt like getting any mist. but i remember reading somewhere that a mist is actually better for the plants. this makes some intuitive sense to me, as dissolved CO2 isnt really CO2, but an equilibrium of CO2, H2CO3, HCO3--, and CO3--. i know some plants can use carbonates for carbon, but i dont THINK (please correct me if im wrong on this) all of them can. so 1 mL of mist is 1mL of CO2(g) in the tank, while 1mL of mist reacted is at least partially carbonic acid and carbonates which may not be bioavailable (though as plants remove the CO2, some of the other forms will convert following lechatliers principle).
so basically, im asking is there a benefit to misting with just a diffuser vs fully reacting in a reactor?
While many species can use indirect bicarbonate, they all prefer CO2 over that.
When light is high and CO2 is limiting, then they go after it, as you increase CO2[aq], then the difference in growth is the same in higher KH's vs lower KH's. At lower CO2 and lower KH's, then the plants will use both and a tank with more KH and low CO2 will have more total carbon available.
But this is due to the CO2 being limited, not so much pH or KH directly.
You can see the growth as measured by O2 production converges as you increase free CO2 in the water(pg 765):
This happens at about 0.5 to 0.6 mM of CO2.
Which is about 20-30 ppm of CO2. But these are 3 very aggressive easy to grow weeds. Other species will need more CO2 to get to that point.
So at low CO2, more KH is good for growth(source of carbon).
At high free CO2, does not matter. You can see this from the graph in Figure 4.
Growth is the same and levels off(saturates). So at that point on, the CO2 is non limiting. Same in figure 6, after 400-500 umol of light, CO2 uptake stops increasing. So adding more light than this is not going to produce more growth.
At least for these weeds.
At the 0-100 umol light ranges, there are huge differences in growth rates however between those 4 weedy plants. At low light, the Hydrilla can really really growth much better and removes all the CO2, leaving only the KH left which takes more energy and work to assimilate.
So plants compete for CO2 and light. If those are non limiting, then you can test ferts.
Likewise, if the ferts and light are non limiting, then you can test CO2 or KH.
Same deal again with CO2/ferts being non limiting and then you vary light.