Calcium Deficiency or something else?

[dogwood]

I'm assuming it's a calcium deficiency since they are indoors but advice would be appreciated. This plant has brown spots and the bottom fan leaves have yellowed. My 5 other plants do not have brown spots however they do have some yellowing tips.

 

[SvembleGrow420]

These "rust" spots could be calcium deficiency. this doesnt only come from a lack of calcium but can also be a result of wrong PH in your medium. What soil and fertilizers do you use?

 

[LoveGrowingIt]

A picture of the whole plant might help.

 

[dogwood]

These "rust" spots could be calcium deficiency. this doesnt only come from a lack of calcium but can also be a result of wrong PH in your medium. What soil and fertilizers do you use?

They are in fox farm ocean forest potting soil and I'm currently using Big Bloom fertilizer in distilled water (half the recommended dosage). All of their waterings I will use distilled water. The light on them currently is not sufficient for 6 plants so I have a new light coming tomorrow from AC infinity. The temp on average is 75F and humidity average is 60.

 

[dogwood]

A picture of the whole plant might help.

I have also noticed they are starting to slightly yellow on their tops as well.