Ok, I am using Epsoma Organic Cactus Plant food, it's NPK is 1-2-2. I want to make a solution that is 2x stronger (2-4-4) The bottle says add 7ml per quart of water. If I use 2 quarts of water for one watering, I would want to put 28ml in, right? I'm very scared that I'm gonna mess this up and poison my plant. It's my first grow and it's in its 4th week of flowering so I'm being extra careful. Thx