I have an older spa, early 80's came with muh house...?

Question:It doesnt have a built in pump to backwash it. SOOO. is it possible that I could use the pool pump? Put the creepy hose in the spa and basically suck the water into my pool?
Would this have negative effects because of the different chemicals?

Answers:
yes possible...spa 300-500 gallons vs pool 10,000 gallons or better...not a big factor with the chemicals here. most spas have a site in the plumbing to connect a garden hose and gravity drain the water out, turn off heater element so as not to burn it up when dry. never heard or backwashing a spa.
just replace the water every couple weeks or months depending on use.