Sea Hare's work great but you gotta be careful and watch them. They are prone to ether eat themselves out of food or getting stuck in powerheads and perishing.
Going off of the other thread about filtration I'd say you definitely need to add some phosphate removing media, as skinz suggested. I think implementing an effective way to remove the waste from the water will yield better results overall in the long run than adding livestock specifically for eating the algae.
There are many different types on the market, most require a reactor to work most efficiently. I personally use GFO made by Brightwell aquatics. In addition, I use Ecobak bio pellets. My phosphates are always undetectable and my nitrates are 5<. Do some research in some different threads and you'll find a ton of user reviews.