hi tone
salt in your pond is good for over wintering your fish if you dont heat , can be of a huge benefit in the spring when temps are up and down and stressing your fish no end, it is a far better preventive than it is cure and if you can prevent it then you shouldnt have the use for chemical treatments. most treatments can be used with salt even FORMALIN

, ( if you dont belive me ask duncan gritthis aka koiquest) at what concentration is up to you i personnally used fmg with salt at approx 1/4 oz per gallon on white spot that a full dose of fmg on its own did not cure. you will always have arguements for this topic some do some dont . if you were setting up a new pond i would go for salt just to help with nitrite toxicity which wont just cause your koi damage at the time but will also cause long tiime damage the kidneys for example. as for removing salt from your pond if you dose at 1/2 per gallon you need to change approx 220% of water so if you change ten percent a week which would be part of the cause for a lot of koi keepers it would take about 22 weeks diminished returns i think its called . i personnally use salt when needed, this time of year and into spring when the weather warms and stabalises a bit then i will stop topping up salt with the weekly water changes about ten % when the pond temp is up and running and fish are feeding as normal i will start to do 15% water changes every third day ( i have a very low kh so need to keep topping up the tap water if not my ph crashes) at this rate it will take me approx 45 days (a month and a half ) by the end of june the salt will be gone and the fish can have hopefully five maybe six months with out salt unless its needed.

cheers paul