N-Rich does work quite well. I typically use N-Rich to enrich 2-day old brine, but I'm sure you'll have no problem with adults. The density I use for 2 day old nauplii is a max of 100,000naup/L, with 2 mL of N-Rich per L of water. I'm not exactly sure what density you should enrich adults at, but the density you grow them out at should be sufficient. The nauplii are enriched for 12 hours to be completely saturated- adults may be able to get away with less time(6-8 hours?). Either way, enriching with N-Rich has given me fantastic results with a variety of livestock.