Algae stuck in divots of pool liner

[imaitrt]

I believe I have some form of mustard algae. I am a Bacquacil user. My problem is that the algae is stuck down in the divots where my sand has settled. It feels like gritty sand when you run your feet over it, but it is adhered to the pool liner. From there, the algae just continues to grow. Any suggestions on what I can use to get this loose?