As mentioned, the halimeda is a calcerous algae but unless in a high CaCO3
demanding tank, simple weekly water changes should provide all the chem the algae will need to prosper. It is more often in new/low nutrient tanks that will cause most all macro algaes will not do well.
The puffer will ignore the algae and the coral beauty will nip at it a bit but if there are no true herbavors, then you will end up removing it as it grows which is whem it is most beneficial anyway. When you remove/harvest the algae, you also remove the pollutants with it. If/when the fish eat the algae, the impurities do not leave the tank
, sea grass/turtle grass is very hard to establish in a captive environment. If possible I would stick with the chaetomorpha if you can find it.