Manual removal. Only buy the crabs if you want them in your display. Same applies to any potential fish that may, or may not, get recommended. Crabs, fish, may eat it, or may not. Thus me saying only purchase if you planned on having them. As an aside I personally know a few hobbyist who have had good luck with pithos crabs.
In any case you have a 40 breeder. Great sized display. My suggestion is to just spend a couple hours here and there and remove manually. Similar approach to GHA. Within a couple weeks it will more or less be managed or all together removed.
- Put on some calm music of your choice
- Few towels
- Bowl of rodi water to rinse
- Nitrile or glove of choice
- Step stool or ladder if needed
- Net
- Small scraper, dental pick, with handle to scrape rock
Pass 1 - net any floaters
Pass 2 - focus on larger pieces, reach in, gently take hold, and pull while slightly twisting left to right - it will come off
Pass 3 - focus on hard to reach pieces, reach in, take hold if you can, if not pinch to pop, and pull off piece you can
Pass 4 - focus on difficult pieces to reach or that are small, use scraper, dental pick, tool, and scrape off
Pass 5 - net any debris
Rinse fingers in bowl as needed
This is more or less what I did when I had an outbreak in my 29 gallon biocube. It was so bad that I had pieces floating around in the currents

Do not worry about popping the bubble algae as there is no proof that it releases spores. This has been discussed a few times with a recent talk on reef beef by Rich. It is similar to my experience when popping them - nothing happened nor did it spread.
The long and short of it is that buying so called natural predators may, or may not, work. So only buy them if you want them. Other than that practice nutrient control and manual removal. The algae will be gone in no time spending a couple hours a week on it.
Honest.