For what is worth, the way calculating the dose is described in that article does not seem correct to me.
Parts per million are equivalent to milligrams per liter in other words you need to multiply the PPM by the volume in
Liters not gallons.
So if your tank is 90 gallons and you want 30 PPM as described in the example you shall need:
90 gals x 3.7856 Liters per gal x 30 PPM = 10,221 milligrams not 2,700 as mentioned in the article.
Having said that, assuming Thiel used his calculation for the determination of his dosing I suggest you continue making the mistake he did, otherwise you may overdose.