The Spirit Bloom one isnt a good spot... Its way faster doing the chest runs on the spawn area to the left after you port down. There is 5 cave chest spawns and 4 bloom spawns in itself. Just run around doing the patrol missions and if possible combine it with Vanguard bounties. Especially the ones that involve Fallen kills like collecting 200 Ethers, headshots or any kill bounties will do too. There is a group with the Captain that gives 25 at once. Usually the Bloom itself respawns each 10-20 mins and chests do randomly ranging from 1 minute to 1 hour. In like 4 runs and 1 hour I got 50 Blooms aprox. Again all depending on luck and RNG.