so small tank dun need skimmer la...regular water change will do...those guys at nano-reef take care of their pico without any skimmer as well...if really water parameter goes crazy...juz do a 100% water change....as for water topup...if budget permits....getting a iceprobe will reduce the evaporation.....if not u could diy a dripper or get a auto water topup system....i would recommend getting the iceprobe...keeps the water parameters more stable(buying buckets loads of distilled water ain't cheap either!!!)As for the sps....u do noe how demanding they are when u got them right? but it would be fantastic if u can keep them healthy..!a... do update us on the progress...