Hello,
First of all, you should realize that hair algae is caused by poor CO2 and has nothing to do with low nutrients. As an aside, lowering the nutrient dosing under conditions of CO2 deficiency can sometimes change the course of events such that a nutrient deficiency can cause the disappearance of the symptoms of CO2 deficiency. All that means though is that you will suffer the symptoms an algae attack due to low nutrients as a substitute headache.
So you need to be sure what algae you are talking about. All types of filamentous algae such as hair or thread are CO2 related. If this is confirmed to be filamentous, then it means that something is wrong with your flow/distribution because the CO2 you are injecting is not reaching the plants. It might also mean that the dropchecker is not yell when the lights go on. If that happens then the fault is being incurred when the lights go on and that having it turn yellow later in the photoperiod cannot erase the faults incurred earlier.
Secondly, the speed of growth of a plant in no way correlates to the overall health of a plant. Plants that grow slowly are often healthier than those growing at a faster rate, because some conditions that generate high growth rates also cause plant damage and encourage algae. You really need to completely obliterate this idea from your thinking, because it will lead you to take the most inappropriate actions 99.99% of the time.
In any case, CO2 is not toxic to plants, so if there are no fish in the tank, there is no limit to how much CO2 you can inject. The limiting factor will be cost of gas replacement.
You should verify the algae type by checking
James' Planted Tank - Algae Guide
Note the corrective action listed for the type and take appropriate action. Most of the data on that page is accurate.
Again, I suggest that you review flow and or distribution.
Ensure that you do not have overzealous lighting. If so reduce the light intensity.
Cheers,