9 plants in 1m² / 2 King's Juice

Hello, can you upload pictures with better looking at problem spots. Brown spots can be several reason, Your EC is high for this period and for Green House Feeding nutrients. For that line i think 1.5-1.6Ec max , i will go higher only if you have CO2 tank and lots off light

you should not have to flush. adjust formula slightly based on observances and timeframe and irrigate with a little more than the typical 10% runoff for soilless. it'll change the substrate concentration almost immediately - maybe about 80% there the first then nearly 100% the 2nd irrigation? Excess runoff will speed up that process. Soilless is similar to hydro in this respect of a fast changeover. if religious about the runoff before this point, it cannot build up concentration of minerals in substrate, therefore any tox or deficiency you observe is due to formula over time -- the longer it takes to show up, the smaller the change needs to be to fix it. asking others' opinions is good, but always look over a leaf symptom chart yourself too... spots without interveinal chlorosis can be calcium related. if interveinal chlorosis accompanies the spots, you can lean toward a magnsium deficiency. Mg is a bit of an oddball. deficiencies start 30-35 days or more before you see the symptoms. so this is where keeping notes about how you fed throughout grow helps. you shold look back at how youve provided Mg and make a more informed decision. I use that only as an example... HEre, i see yellow tips which could be the start of p-tox, and that could also explain some spots showing up. This is a slowly progressing issue and you are fairly late in flower, so i'd have patience. let teh symptoms be more obvious before making a choice, unless you are confident about it based on your own observations and referencing a leaf symptom chart. (google drive link in my GD profile comments has one - sort comments by newest first, or google image search) Mulder's chart is another layer of sophistication to learn.. you can see how adding some nutrients requirs you raise another one... or if by adding a specific one, it may make another one less available -- stimulative vs antagonistic relationships. again, this is where trackign what you fee helps greatly. if oyu know you added a bunch of P and the things listed in mulder's chart related to it start to show the symptoms, you can feel very confident about your perceptions of what is going on and act immediately while expecting good results. Even mostly helathy plants show some sort of symptom late in bloom phase. as long as it's minor and not progressing quickly, you can be patient with it. these are "good" problems. the next cycle armed with this learning experience can result in a formula that avoids it completely... or even slower progression / less severe symptoms.. there is a bit of diversity related to this, so some plants may look perfect, otehrs may not... somethign that works for most is all you can do.