What's happening with my plant?

[weeed]

BubbleGum Auto seed
Beginner First plant
day 38
soil is Canna Terra Profesional
temperature is 22-26C
water is from the tap and filtered (have no ph tester)
light is 40w (I know now it is too little, have 1 the same but heat is to high)


Around day 24 plan show dark spots on low leafs and start yellowing It was after add first time Biobizz bio-bloom and after move to another growbox. Start reading and after few days buy Calmag. I'm using this till today but It not really working because new lower leafs yellowing and see lighter spots on flowers.

 

[Pushrod Monkey]

Potassium deficiency

 

[weeed]

So i should invest in PH tester and test water?

 

[weeed]

Potassium deficiency

Bio-bloom has potassium, I'm not sure it is that

 

[freezeland2]

Bio-bloom has potassium, I'm not sure it is that

If your ph is way off the plant can’t feed on that bio-bloom. Hence potassium deficiency.

 

[N1ghtL1ght]

temperature is 22-26C

could be warmer + plant is looking chronically overwatered

 

[weeed]

Oke I will try to less watering and check ph. With second lamp temperature is around 29-30,5C