  Ultracold gases of highly magnetic lanthanide atoms have enabled the
realisation of dipolar quantum droplets and supersolids. However, future
studies could be limited by the achievable atom numbers and hindered by high
three-body loss rates. Here we study density-dependent atom loss in an
ultracold gas of ${}^{166}$Er for magnetic fields below $4\ \textrm{G}$,
identifying six previously unknown features which display both a strong
temperature dependence and also sensitivity to the polarisation and intensity
of the light used to optically trap the atoms. This detailed knowledge of the
loss landscape allows us to optimise the production of dipolar BECs with more
than $2 \times 10^5$ atoms and points towards optimal strategies for the study
of large-atom-number dipolar gases in the droplet and supersolid regimes.

Quantum Gases