High PPM, day 18 flowering.

ok im just wondering if it is ok to have 3 flowering plants at a ppm of 1800? I have gradually increased the ppms every 2 days for 4 weeks leading up to this point and the ppm is currently 1800 ok my 3 largest females and my smaller one is at 1200. I am thinking about topping up tommorow with ph balanced water to the bigger one and continue for 2-3 days then go back to regular adding of 1800 ppm solution. I am day 18 and I want to use Kool bloom or bud boosters should I go out and buy some right away and start using it also after I am done adding some Regular water to my babies??

The buds are all small thumb sized buds everywhere so I want to time it right so they get some good growth..

HELP OR SUGGESTIONS APPRECIATED THANKS!!@

It's fine as long as they are not burning, but it seems pretty high to me.