No. No algaecide in pools. It causes more problems (metals) than it solves.
If your pump is not working, then you will get low pressure, sand or not. Get a new pump ASAP.
https://www.doheny.com/
Not sure where you are located, but I highly recommend a 2 speed pump or Variable Speed Pump.
#2. Go to
https://www.troublefreepool.com/forums/
It is the "Pelican parts" of Pools. They can help you go from Green to Clean. They don't sell anything, it is non-profit and run by pool owners sharing how to run a pool.