with it that high if you use pucks it would start to get up so if you did get algae it would be difficult slam, the calculation is easy but if you do when you get back you will probably be using 70 as your new CYA even though it will not add a full 10 of cya. So I like slam level and cover if you can, if you can't cover I would consider a few pucks, Also water replacement would be pretty easy if you had to, my big beef would be loss of heat as new water would be colder, if you have heat or are not big on night swimming it may not matter.