I also run carbon 24/7. I run 1/4 cup per 25g and change it out every 2 weeks. It's not needed but can help. I do wonder if running it every now and then as apposed to 24/7 would be better. If you have a LPS/Softie reef, I would not run carbon at all. Play around with it yourself and see what fits your reef. Oh, if you feed alot I would run carbon. Better safe than sorry.
If you don't want to run carbon you could run polly filters, also great for pulling out junk and metals. They will cost more to run though. They are good to have one on hand incase something happens to the tank and you need to get something in there to help out. For example, if your glass heater breaks, pop in a polly filter and it will more than likely save the day. They also turn colors to let you know what they are pulling out.
HTH
Jason