Red Slime is a bacteria, not an algae, the product description is misleading.
I have a couple of concerns with this Red Slime Remover. First of all, the product's active ingredient is Erythromycin, an antibiotic. This will kill beneficial bacteria as well.
Secondly, Red Slime Remover only kills the Cyanobacteria (red slime), it does nothing to correct the conditions that led to the bloom in the first place. This more than likely means that you will be buying another tube of the product down the road.