Should I get another 100 watts (2x4 space) for a total of 300?

In short: Should be fine Also looks like you asked this question twice? Maybe GrowDiaries is posting it twice as it has the same weblink... IDK questions part of website seems to be breaking again. growdiaries.com/grow-questions/67227-should-i-get-another-100-watts-2x4-space-for-a-total-of-300 200W is good, but if it has a shity spread its not the best lamp them, and maybe two of them at lower power would be better. Ideally you want aorund 20-32W per SqFt' 2x4 = 8SqFt' 200W / 8 SqFt' = 25W/SqFt' its smack dab in the middle of the range that is good. If your not using any CO2 then I don't think you need anything more. I use two lights in my tent for better more even spread of the light but I don't use them above 40% dim in Veg or 60% dim in Flower as its to much light. Best to reference a PPFD map for your light in question in the same sized tent. Your PPFD and DLI should be your main factors on what you do with lights, not so much the wattage. wattage is important just not as much as its PPFD and DLI. Google these things if they are new to you. Good Luck!