First time grower looking for a bit of advice

Hi

I'm have an issue with the plant I'm trying just now. It's not much to worry about at the moment but I'd like to try and catch it before it gets any worse and really just looking for a second opinion.

Here's what I have....

OGKush
600w digi ballast and 600w dual spectrum bulb, the ballast has been set to 400w
Tent size is 90x90x175
Coco perlite 70/30 mix
Watering schedule is feed feed water, each time 1L with a good run off. It gets fed or watered everyday.
Just now the feed is 2.5ml Canna A+B (2.5 of each) 2ml rhizo and this time 1ml Cal mag.
pH is usually 6 but today I downed it to 5.8
Background EC is 0.70
Working EC is 1.552
Day 29 (second week veg)
Temps usually go form 27 in the day to 21 at night though there is a hour or 2 during day time when it can reach 30.
Humidity 40-50%

This is the first time growing anything in coco and using so many different amounts of nutrients and to be honest I'm still trying to get my head around it all.

4 days ago I noticed some small brown spots on the second set of leaves so it's at the bottom of the plant. The leaves are also going yellow aswelll.

Since this is starting at the bottom is this a nitrogen deficiency? If it is what do you think has caused it? Is it locked out or just not enough being added?

The last pic is the new growth but just after getting topped. It looks fine apart from that.

Brown spots from calcium deficiency. Looks like it was only on lowest leaves so now that you have added calmag to feed problem fixed itself. Top leaves look good no more issue.

Nice one thanks ks mean gene. That was a couple of days ago and I can see it's picked up a good bit.

Should I continue the application or wait till it shows signs of deficiencies again?

I always though Cal would show up on new growth first as it's semi-mobile? Is the plant moving it from the bottom to the new growth then?