Help a newbie diagnose

This is my first grow and I would love it if you guys could help me to find out why my plants are sick, the symptoms are: necrotic spots, yellow spots and impaired growth. The spots attack primarily older leaves but some sprouts are deformed and growth impaired. Spots appear random, there is no pattern such as tips or between veins are specially impaired. Some stems are also red/purpleish. I use Canna Bio Vega for fertilizing where the NPK is 3,5 - 1 - 5,5 but when i read nutrient index thoroughly i found out that the P stands for phosphate in my fertilizer, isn't supposed to be phosphorus? I uploaded i few photos so you can see for yourself, sorry for bad quality I had to use my cell phone since my camera got broken. Thanks a lot.

what is ph?

Unfortunately i don't have a ph meter, but i know the soil i bought was 6 and i know that my tap water is very soft.

do you let your water sit for 24 hours b4 youu water them?

No, why is that good/bad?

you really sould it cleans the water from any chemicals and makes the ph nutral

Hrm, i had that problem before and cal-mag fixed me up. I dont let water sit either but ive heard thats the best way to go, and i plan on moving my setup around so that space allows for me to do this. But i would suggest deffiently checking your ph because when i had that problem it wasnt my ph. It was a defficency of nutrients. Yours might be a ph problem, im almost sure of it.

Could anyone else confirm that this is a cal/mag deficiency? So, I check the ph, if it's of i try to balance it with something alkaline like woodash right? But if i have a good ph, am i supposed to fertilize more or do i need to find an extra cal/mag source?