I have had this polyp for about 1.5 months. It is attached to a small rock but the polyps haven't gotten any longer. They are about half way down my 55gal near the filter and have good flow. They seem to look fine. My light is marine pro led with max intensity set at 50% which a gradually worked up to from 35%. SG is about 1.27 but been around 1.28 for two weeks. (Going to bring that down a bit). Putting aside whether I actually should have this in the tank...do these polyps get and longer or do they stay small?