while tubeless rim and tyre technology has matured in recent years, sealant still remains a weak link in the system (it will no doubt improve as the market and competition grows). i store sealant in the bottles it comes in, but squeeze the air out before tightening the lid, or pour it into several smaller containers. can't recommend any particular sealant, as i'm looking for a good one myself (that works well in higher pressure tyres)!