HELP PLEASE: Yellowing Leaves with spots

Thank you for the insight snowball. I will definitely use that ratio with my next grow and throughout the remainder of this grow. Now the only problem I have is, the Muriate of Potash doesn't have a feeding ratio on the bag and nor could I find it on the internet. They say to just mix it in the soil and water the soil and it'll feed from there, but I'd rather use it as a liquid. So what do you suggest as a ratio for that?

Oh and +rep for the input.

if its a powder kind, and it says hi yield across the top then its npk is 0-0-60 per tbsp.

sooo a 1/3 strength would be 1tsp = 0-0-20
sooo i guess you can add it in 1/4 teaspoon increments = 0-0-5
you do have those measuring thingy's for cooking right, there like a dollar at the store

lol. Yeah I have them. I'm the cook of the house. It does say Hi-Yield across the top. So basically I'll need to use 3/4 tsp for 15 then. But to what ratio of water, a gallon maybe?

Would it be to a 3/4 tsp: 1 gallon? And it's the reddish/pink kind that looks like salt grains so to say.