NOOOOOOOO!!!!!!
WARNING!!!!!!
Always add Si first before anything
silica will cause major ph changes as well as create "Nutrient Fallout" if not added BEFORE all other nutrients
so fill the res
add the Si and allow to circulate for about 30min
then add your nutrients
wait another 30min and then ph adjust
Si will shoot your ph through the roof
I use
botanicare silica blast and I use at 4ml per gal that sets my ph @ 6.0-6.1
even with
Veg+Bloom that I am using now
I hit the same @4ml per gal
every Si is different and more or less consentrated so you have to experiment to see how much to add
I would actually fill a gallon jug with ro and run the suggested Si and your base right now
and check it every half an hour
till it completely settles
that will tell you how much ph down you may need or how much less Si to use
I like the cell wall strengthening properties of Si but I pretty much solely ise it for ph with the added benni's
I run Si all the way up to 2 weeks before harvest
I do a first flush and allow
the medium to completely dry then I start feeding water only for the last 2 weeks