The co2 is great advice, but I personally would try other things. I am very against co2 because a planted tank can be easily balanced without co2. And just adding co2 isn't magic, where you start adding it and it solves all your problems. You sould know that starting to add co2 will 9 times out Of 10 require you to adjust everything Else to rebalance your tank. Then if you decide it's too much work later and stop using it, you must re adjust everything again. Just throwing some things out to consider before you make the co2 jump. Consider your personal schedule also and if your life becomes more hectic do you want to continue co2. Co2 is not a big deal to some but, for some it's a deal breaker for their personal schedules.