is this root rot?

To me... it looks like Cal-mag has been locked out.

Yeah,,,,I agree.....he has several problems.
Ca/Mg
Low N
High P
Bad soil
pH from nutritional abuse.....Kind of a daisy chain.....Everything is screwing something else.

You can pick up a tds meter for around 30$ they are a must. on your next run try a little less vedg time in those buckets. if you took a clone then your clone wont have that same problem because it doesnt have a tap root. clone roots tend to grow outward not down.

Well I flushed one tonight and put 10 gallons through her my tap water sat out for 24 hours but it Ph test at 10.9 and when I put it through my soil my runoff test a steady 5.9 I multiple tested it throughout the flush. The last gallon had 1/4 the normal dose of cal-mag. The buds are still growing but what am I looking at here? Are they salvageable? Will I still be able to harvest them? Man this sucks I thought my first grow was going great until I ran into all this still I'm trying to learn. My next run will be 2 transplants. Small pot, medium, then 5 gallon.

what I found with five gallon pots if the salt levels get real high you would have to run about ten gallons of water through them. The tds meter is very important just for this sort of thing. three transplants sounds good.

I did run 10 gallons through the one. Tomorrow I'll flush another one and lastly Sunday I'll flush my last one. I hope I can still harvest these. Oh well I'm glad I'm learning