
...Rayuki, this isn't N-tox mate, like Pepe' says, no classic claw tips....... zero sign of nute burn on tips, particularly the new growth, so that's out,... lowers with "teeth" and tip browning, more likely some minor K defc.,... (K is mobile within the plant , so will be pulled form older leaves to support new growth),... about the N in the soil, it depends on what the source is, but only soluble form will "rinse out", insoluble won't,.. it's the soil microbes that need to break insoluble forms down into forms the plant can absorb (nitrate, ammonium- NH4+)... this is in part what's behind the delayed release effect you read about,... meantime, stop flushing! this is an emergency method mainly, to help correct badly off pH and/or heavy nute build-up that's starting to kill the plant,... neither is the case here,... that said, an in-pot pH reading would be wise,.. you'll need a good pH probe for that (Accurate 8 is a nice model for the $).. like Micron mentioned, a pH meter (for liquids) is critical! Not having means to test things is a disaster waiting to happen,.. An nutes "self-buffer pH" only in solution, and with recommended RO/Di water,.. add hardness in there, and the ability is taxed as is,.. your water is nice though at that ppm,... enough mineral content to help with pH buffering (CaCO3, it's the carbonate anion that's involved with buffering)...... that 700ppm includes the water's 130ppm? that's light feed, and the soil, now over-purged of nutes, is likely not much help now,.. So, raise the feed up more, say 100ppm, and watch the leaf tips for signs of yellowing, indicating early nute burn,... I don't know all the damn AN products NPK#'s, so do some math and find out what K is going in from all inputs,...
What lights are you using, and how far away? That compressed look is more of an intensity issue perhaps, too strong,.. shortens internodal lengths,....
Don't bother with dolomite for pH correction, it's too slow acting,... even regular lime won't act right away (dolomite has slightly different chemistry, hence the slower release), and until we know what the soil pH is, any fooling around with corrective products is more likely to make matters worse, not better, unless you get plain dumb lucky! there's no sign of
badly off pH, other nutes defc.'s would likely be showing by now,... it's still in play, but my guess is it isn't critical-bad,.... You can get a crude idea from watering-only run-off, but again, with no meter or even higher resolution test kits, you're stuck,... try the strips anyway if you like, if it's within the resolution range, it make help eliminate things some,...