weird black spot and yellowing in new growth leaves

[LordD]

Hello, I have a question about 2 of my plants, today I found that one have some small black spots on the leaves, really small and it had like 2 "long" spots(around 2mm x 0,5mm) I think that was some kind of bug, sadly it fell from my hand to the garden so no photos, and it had some kind of silk on the back of one leave that I removed

the other one have some weird yellowing on the new leaves but it's growing normally actually its the biggest of the four

I have do some research and it don't look like calcium deficiency(black spots) nor leaf septoria nor iron deficiency(yellow-ish leaves), I also did a rough ph test and the soils it's supoce to be neutral(need to buy some ph test strips)
here are some photos, sorry for the quality

 

[9fingerleafs]

They kinda look slightly underfed. To me it does look like magnesium iron deficiency but tell me more about those plants. How old are they. What pot size? What medium and nutrients?? Anyhow a bit of calmag should perk those babies up

 

[LordD]

they are 2 months old, the pots are around 8" wide x 7" tall, they are in soil, and I have used a a liquid fertilizer that is 10(N)-50(P)-10(K)+minor elements, but I have used little of it because I don't know if that much phosphorus is bad for it(I have another one that is 11-27-11 that is granulated, btw I don't know how fertilizers work over thare so those numbers are percentages), I know I have to get one with more nitrogen for the vegetative stage but haven't found, also I can't really use comercial brands that are sold in the USA

 

[9fingerleafs]

What kind of water you using? Definitely get some calmag, it’s 2-0-0 and has calcium magnesium and iron

 

[9fingerleafs]

Plus you can mix with water and spray it

 

[LordD]

well, tap water really, here tap water is pretty good and the rest of the plants haven't complaint(nor the fishes), I will try to find something like calmag, in the meantime I will go full "organic"

 

[LordD]

well epsom salt is magnesium sulfate, internet say it can help on make the plants bushier, improve bloom and make the plants greener, but dunno, btw I found a calmag brand Technaflora, anyone know if it's good?

 

[LordD]

well, the black dots disappear and the yellowing fade to green, any way I will search for a calmag, thanks

 

[9fingerleafs]

It’s the most essential nutrient/additive in both soil and hydro specially if using RO or low ppm water. If you can get botanicare calmag or GH calimagic would be best. Tried and proven products

 

[LordD]

I found the botanicare calmag for $60 the gallon, and the calimagic for $20 1 quart, I think I will go for that

 

[9fingerleafs]

I’ve been using a one quart for two years and still got some

 

[LordD]

well, it's overpriced here, but if yours have last that much then it's a good investment