The unpredictability of different operational parameters has rendered finding the optimum conditions for carbon nanotube (CNT) growth particularly challenging. This study attempts to explore the effect of temperature and pressure based on the growth regimes suggested by Lebedeva et al. (Carbon 2011, 49, 2508-2521). While the absorption regime resulted in premature growth, the surface- and diffusion-controlled ones showed a remarkable growth of carbon products. Along with these two regimes, the diameter, array height, and quality of CNTs generally increased with an increase in temperature, but these parameters experienced a reduction near the boundary between two regimes. Just before this reduction, the location may be considered as the optimum condition for growing tall arrays of high-quality CNTs. The quality and quantity of the grown CNTs improved as the pressure increased up to 7000 Pa.