Why would a water change to big kill the fish? If you have a cycled mature tank and watch your feeding meaning you don't over feed to the point were food goes to the bottom and eventually rots and releases ammonia in the tank 20 to 30% water changes once a week should be fine and you should always have a health tank water chemistry wise.Well I'm mostly concerned about my Asian glass catfish
which require clean water and tank
my other fish aren't as fussy but I was wondering if it
will give me a diesease free tank?
Obviously a water change that's to big would kill the fish
but anyway
Good advise! I'd like to add a little to that if I may. When you test your nitrates and you feel they are to high more then likely one small water change is not going to help. Let me give you and example to help you better understand what I'm talking about.rather than worry about doing too much WC, you should just do the amount you need.
keep a liquid test kit handy so you can keep an eye on your WP (more specifically, the nitrates. assuming the tank is cycled)
when your nitrates look like theyre getting high. do a 25% WC. when they get high again, do a 25% WC. moniter yourtank for a month or two, and you will notice a pattern in your cycle, and can judge when to do your WC.
Good points! With the water changes I usually try and get the temp about the same as the tank when its coming out of the facuet. However if you got a larger tank like bigger then 10 gallon and your do a small water change like 20% its ok you use cold water I have found that fish sometimes like that and in the wild the water temp is constanly changing anyways. If your doing larger water changes or your tank is small make sure you match the temp feeling with your finger is good enough. If your were to put that volume of cold water in your could shock the fish.as long as you take the proper precautions, no, there is really no limit.
just make sure you have the temp right (doesnt have to be exact, just close)
use a good decholrinator (if youre not using well or aged water)
and dont let your filter dry out during the process