What is the best planet tier/type/etc and biome for gathering saltpeter?

[Ratchel]

Bob's Regen Farms. Come give us a visit! Located through TNT farm hub and T5+ network

Bob’s Farms Accessible through TNT Megahub currently has the T1 farms (TNT Farm Hub) and our T5-T6 farms (TNT Higher Tier Network). The farms are fully protected with brick and glass. No water or holes to worry about. Sign for portals will read “Bob’s Farms” at hubs. Portals are available for 1x2, if you would like a different size please let us know. On Galan Universe’s Largest Growth Farm (Shimmering Orbs) and Wood (Bark/Sap) farms. On Norkyan we provide Foliage (Inky/Starberry) and Corrupti…

Just use my gravel farm. I get little over SS on one persisting pie.