Kind of hard to figure out exactly what's going on but am I right that your ppm is only 195 - the 85 your water is starting at for a grand total of 110? Actual nute levels should be around 300 - 400 for those plants.
Does that mean mls per Liter, gallon?
Any particular reason you are going to change nutes so soon? I would just boost up the levels you have in there and keep going. You don't have to change every week especially when the plants are so young as they don't eat hardly any of the nutes and you're just tossing away good nutes and money for no reason I can see.
Are roots growing out of the net pots yet? The nute level should be an inch below the net pots if they are and maybe an inch above the bottom if not.
Now to your lights. Are you keeping them as high up as they are in the picture? With 150w HPS they should be about a foot above the tops of your plants at most. I run my 400s a foot above.
One 12 or 14" oscillating fan would work better than all those little ones but they will do. I bought 3 of those exact ones a couple months ago for under $2 each. Mine are USB but I'll wire them with 5v wall warts so I don't need to use my USB/110v converter like I am now to run one to blow into my light reflector hood that holds 2 - 400w HPS. Are yours USB and if so how are you powering them?
I don't know why they use such huge net pots in those pails. 5" ones would do fine and are higher up to make more space in the pails for nutes tho with a recirculating system I guess it doesn't really matter.
Lots to think about.