I will second most of what David has written. Just be aware that for a fish to graze bubble algae, it has to be able to get a hold of it with its teeth. Some bubble algae are easily grazed by a fish like Siganus, others are much more resilient. It will be a challenge to find a smallish fish (70 gal tank) that can eat biggish bubble algae.
Diadema urchins will graze what bubble algae they can get at, IME. Diadema is thorough grazer and will graze most plants, with some notable exceptions. A downside to Diadema is that it will outgrow most tanks in a fairly short time, and becomes a "bad citizen" (coral eater) when it reaches its growth limit in a tank, IME. I'm currently trying Echinometra urchins. These urchins don't grow as fast as Diadema. I expect but can't confirm that they would be an effective control of bubble alga. If you try Diadema, only purchase one, in a few months it will have spines 7" and longer and will be grazing most of a 70 gal tank every day. I can't recommend a stocking rate for Echinometra lacunter, but it will take a few to get much immediate satisfaction.
Probably the best control of the bubble-type alga is not introducing them to the tank. However, the conditions that live rock is kept in (low light, high nutrients) during holding on its way to the consumer make it almost certain that rock will be purchased with at least one specie of bubble algae established, IMO. This brings us to the paradox of purchasing imported “live†rock to then proceed to kill much of what is on it through extended light deprivation (“cookingâ€Â) and even more aggressive measures. However, "cooking" may be a possible control, but one most of us who frequent the plant forum have never tried.