AEroponics 3 weeks into flower PPM?

i just boughta ppm meter my laddies are 3 weeks into flower 3-4 feet tall multiple strains norhtern lights bagseed and a seed that a friend brought back from Jamica (short and stalky) iam using tap water with a ppm of 225 out of the tap. Iam using dutch nuts A&B and liquid super juiced. What should me ppm be it reads 925 last night.

What should i expect to see day after day. Will it lower? should i top up every day to a certin ppm? or just add water plain ph balanced to top of the res?

Thanks for any help plants are lookin good a little brown on some leaves

Not sure about the ppm reading, do you know signs of nute burn?

thats pretty crappy tap water, but you should be around 900-1500, just slowly raise it and if you start seeing any signs of nute burn back it down a bit.