How much silicate to cause a diatom bloom

[Asm481]

I am trying to beat prorocentrum dinoflagellates. I have Brightwell's sponge excel and am confused how much to dose to cause a diatom bloom to outcompete the dinos. The bottle gives dosing instructions to feed my sponges but of course doesn't talk about diatoms. I am working on a 75 gallon display and putting three drops in seems like nothing! I don't have a silicate test kit. Is that a necessity or can I save the expense. If I need to test, is Salifert a decent test for silicates?

 

[bubbgee]

When I did this, I just dose half the dropper every day until I start seeing diatoms on the glass or surfaces. I didn't really overthink it. I just dropped on high flow area so it spreads around the tank quickly. There's going to be some precipitation as it is dosed.