Question
Can I use rocksalt in place of pondsalt(seasalt)?

Answer
Hi Tim,
Thanx for your question.  Yes, you may use rock salt in place of pond salt.  Follow the same dosage procedures.  In generally a gradual salt treatment for whole ponds is the norm over large dosages.  You may use stronger doses in a "hospital" aquarium where the fish are exposed to higher dosages of salt for up to 10 minutes at a time.  This is used to kill certain parasites and cure certain diseases.  Do you have access to the appropriate salt levels?
I hope this helps.
Tom