Iron in pool....

Hi everyone

right got a problem with a pool .... The pool is 40 x 20 average depth 1.5 m it has a sand filter and a 1.5 hp pump... The problem is the pool has not been used for 3 years or so, and was thick with green sludge and leafs at the bottom... So I first needed to pump pool water out ... Then I mixed shock chlorine in a bucket and scrubbed the walls and floor and then jet washed all down to look like new😊 I then filled pool from mains pressure so looked good too.. Now the problem .. I got the pool filtering but noticed there was some clumps of rust coming back into the pool, but water was still clear.. Then after a day of filtering i added some more shock to bring the levels up... Oh no day after the pool has switched to a clear green tint. I no i have read somewhere the the chlorine will react to the iron hence the colour.. But my other problem is the the sump skimmers and returns are all in iron pipe work.. I no it's around 30 years old.

will this clear at some point with plenty of back washing or do I need to take more measures..