Hi mate,
The power inherent in The Matrix is that which is our own complicity. This complicity allows the system to hide the truth from us. The bonds of our servitude are forged within our minds. I can only guess that somewhere deep in our psyche we fear the dark, so we can never voluntarily blame the light for any problem. The wild goose chases (fungal attack??) always somehow seem more palatable than the reality.
The mechanism of CO2 failure has to do with the interactions of light, CO2 and the all important enzyme called RuBisCO.
RuBisCO is the agent that captures and transport CO2 to react with certain enzymes which strips the Carbon and combines it with Phosphate to produce a type of sugar called G3P (Glyceraldehyde Triose Phosphate). This is later converted to glucose to feed the plant cells or turned to starch for long term storage.
Now, in the image below, forget about most of the other annotations for a second. Can you see that CO2 has to diffuse through the light green Outer Membrane, through the dark green Intermembrane Space, and finally into the brown Stroma? That's a lot of work for CO2 to penetrate - and remember, that's after it has found it's way through the outer leaf surface and then through the epidermal cells. Terrestrial plants have dedicated air channels that direct the CO2 to the Chloroplast cells. Underwater, only osmotic pressure of the dissolved CO2 gets it to this location. On the other hand, can you see how easy it is for the light to get through? Billions of photons come streaming through what amounts to a thin curtain.
RuBisCO attracts and holds the CO2 (along with RuBP) and transports the pair to a location in the cell where The Calvin Cycle takes place.
Here we zoom into the Cycle. Again, a very complicated system. Just ignore everything else and check the bottom (6 O'Clock position). The produce of the Calvin Cycle is the sugar G3P. See the wheel shape? More light spins that wheel faster, meaning RuBisCO has to gather and transport more CO2 faster. Do you see the numbers preceding the various chemicals. It's a very precise cake being baked: 6 CO2 + 6 H20 and so forth. What happens if you can't produce the right number of CO2? That wheel spins right off the cart and the plant winds up in a ditch pretty quickly. More light generates faster growth so the plant has to commandeer that starch that is stored away in order to keep pace with growth. When that runs out the plant starts to cannibalize itself to find enough carbon to fuel the growth. A lot of those intermediate products we glossed over actually become toxic and do damage internally. That's another reason we see holes, deformation, discolouration, disintegration and translucency. Algae sense this immediately and attack. One way in which the plant can adapt is to produce more RuBisCO, so that it can transport more CO2 at the faster rate. But this may take a week or two. So when you hear people say "Well I turned up the light in my tank and it was OK" that's because their particular plants had stored up enough carbohydrate and nutrients to weather the transition until more RubisCo could be produced and deployed. The plant can also reduce the number or density of pigments to lower the efficiency and to protect itself from overdrive.
Cheers,
,.... but I am enjoying it nevertheless. 
