PPM/TDS is very important regardless of grow system.
The brown leaf tips are a sign of over feeding. back your food off by 100-150ppm.
The yellowing of the leaves is a result of your using the koolbloom. It's ok. just add some nitrogen to your nutrients. The nitrogen will bump your PPM up, but because the plant is in need of the nitrogen, it wont burn the plant. Try for the 850-900ppm and use the nitrogen to bump it to 950-1000ppm.
Basicly your plant will need more N as you increase your P and K levels.

When you see your leaf tips begin to brown or curl even slightly, back off the PPM.

When your leaves yellow, add nitrogen (just enough to get them to re-green).

If you see your leaves begin to get dark green and curl downward, back off the N.

When in flower, try not to over do the N as it will hinder flowering and bud production. Too little N and your leaves will yellow and hinder bud production.

If you have more nute questions, just PM me or post again.

Again, as it stands, your PPM are too high right now and you will need more N in your next feed or two.

hope this helps...
GanjaRobPDX Reviewed by GanjaRobPDX on . more nutes or less with blue widow im using 6 x6 rockwool cubes. hand watering drain to waste. 1000w hps in doors. 18 days into flowering. Gh flora. at 1 micro to 2 bloom ratio no grow. 1/4 tea per gallon of powder koolbloom. mixed to 1000 ppm at the present time. do these plants need more ppm or less? more nutes? are they getting burnt? any help much appreciated. im asking because gh's nute calculater says that you should not go over 850ppm. i did that for the first few weeks and just a few days ago went to 1000ppm when i saw Rating: 5