Personally, I think you have more than enough light to grow just about anything. Most of the plants you have will be fine with lower lighting. Instead of spending money to upgrade your light, maybe upgrade to pressurized co2. Your tank will benefit more with stable co2 rather than higher light. Pressurized co2 might also help with the algae that you have. Anymore light than you already have will be hard to maintain a balance with diy co2.