Its fairly easy, and there are MANY different ways to do this. i dont use a vacume at all! heres what i do.
materials:
1) cup
2)bucket
procedure:
1)take the cup and put cup after cup into the bucket. i use those 5 gallon bucket, they seem to work the best. so anyway, you take some water out doing it that way. i ussually change 5-10 gallons weekly. so thats 2 buckets
2) you should already have aged sea water, or freahly prepared sea water. just pour in 5-10 gallons(how ever many gallons you took out).
3) or another way is to use the vacume insted of the cup. so you dont have to keep sticking your hand in the tank. if you have any Q's on this, POST BACK!