You totally should, there’s nothing like some good rain water…. Tap water could never!! Lolol
And not even, I got it down now to where I have so many rain barrels and buckets, and we get down with some bar-b-ques pretty often so I always have wood ash to add into the water and bring up the ph slightly!
I use to do a tablespoon or so of baking soda then I discovered wood ash, and I’ve been using that since !
The amount varies, sometimes it’s about a few pinches into a 5 gallon bucket or rain water sometimes it’s a big handful into the 50 gallon drum .
Good to know , I’ve read that silica is good for lots of different things from support to nutrients and growth to even pest resistance, but I would also worry about adding too much, is there such a thing as silica overload? Lol