Here in the UK they just come in large bags springKnee I have a 1,000 gallon pond and I run 2 bags alternatly to each other on a 3-6 months turn around.
I'll tell you what I'll ring the fishh shop later and see if I can find out the weight., as to salt save yourself some money my friend go to your super market and buy in some cooking salt (never table salt as there are to many impurities).
Here its onl;y like 45p per 3 kg , what I've done is filled a large plastic bucket with a lid so that when ever we need it its there, aquarium salt sometimes claimed as medicated is just salt and you'll pay ripp off prices for it .
If you can place the zeolite in your filter I dont know its size all the better but in the flow otherwise, "word of warning though never heavily salt the pond as it could release the ammonia from the rocks into your pond" plese remember that its vitally important you do ok ?
Dont forget to get that API pond test kit and dont rely on the fish shop for your readings as you need to test your own waters every week.
Dave