Thanks for clearing that all up, and I got confused because Tom Barr seems to be registered here and everywhere lol, shame I do not have his knowledge & yours
Cheers for the tip about 50% distilled water and double the result if it's too high to read, will give that a whirl.
One last question to make sure problem solved, when I purchase the K2SO4, I was planning on making a new Macro batch 500ml "below"
Mix, Shake & Leave to Dissolve Overnight:
4tsp Potassium Nitrate - Replacing with K2SO4 below
41.784g K2SO4 I believe
1tsp Potassium Phosphate
6tsp Magnesium Sulphate
Can the K2SO4 be mixed with the above? I read some fertilizers cancel each other out? So what's the best route? get another 500ml bottle and dose it separate or will it be ok mixed with them.
Also my EI is not 100% daily, as I do Macro one day then Micro Next, so when working out how much K2SO4 to add to 500ml, do I need be calculating for The Estimative Index rather than daily?
This is what the calc says: for 90 lites.
"To reach your target of 7.5 ppm K you will need to add 41.784 g K2SO4 to your 500.0 mL dosing container. Add 18.0 mL of that mix to your 90.0 L aquarium to yield"
Dose these levels 2-4 times a week for EI
I would be dosing it 3 times a week so that method would be correct?
I am so sorry lol, if I sound dumb, I am getting it much more though than I did 24 hours ago.
Just if I choose the option EI daily it tells me to use 17.828 g over 500ml but then I would need to dose that daily. Either way which ever option I go for, when I dose this with the Macro/Micro mix, they wont cancel each other out?
Thanks again to you and plantbrain for your help, hopefully I didn't take to much of your time up lol, just this last piece of info then I can get ordering