It introduce diatoms and diatoms beat dinos for this specific dino anyway
Yep. It allowes Diatoms to propagate and crowd the Dinos out. Then the silicates are all used up, drop in concentration which starves the Diatoms out (they use silicates in cell wall synthesis). It's an indirect method of controlling the Dino population.
You don't need UV for LCA and SCA. If you have facebook, join Mack's dinoflagellete group and there you will find a step by step guide as well as silicate prescription protocol based on tank volume. Took me 3 months to beat SCA but just stick with it. Also, you can use Lynn sodium silicate on Amazon. This is what their group recommends (a little goes further). With the brightwell product, you may have to be dosing a ton.
+1 to the higher concentration 'waterglass'. I used the LOUDWOLF brand (~ 1 ml in 50 ml of RODI) and that seemed to be the difference (for a 90 gallon mixed reef). I'd still get a carpet of diatoms later in the light cycle, but all of the clean up crew came back to life and started helping again.
