If you want to have minimum FC levels (relative to CYA), then there are some options without side effects that you can do. One is to use PolyQuat 60 weekly, but of course that's extra ongoing cost (around $2-3 per week for a typical pool).

Another option is to use 50 ppm Borates since they are a mild algaecide (algistat). We don't have enough experience to know if they will help keep away mustard/yellow algae, but it does seem to inhibit green algae growth at least somewhat. The Borates would mostly be a one-time cost, with some additional for making up for dilution.

Richard