That was one of the first dosing calculators made and the advice is a bit out dated.
I do not use dosing calculators personally.
We have a nutri calculator here that's a good standard to follow.
I think 10ppm per dose for NO3 is good.
I think I dosed 3/4 teaspoon for about 7 years on my 90 gal, (see my avatar) 3x a week.
No need for K2SO4 dosing.
If you use the GH booster, then it's about 1/2 K2SO4 anyway but you only add that once a week after the water change.
There's more than enough K in virtually every tank so unless you have low light/non CO2 methods and/or a very large fish load, there's no cause for any concern.
You'd have to get at least 75% of the N from fish waste before dosing with KNO3 would not add enough K+.
KNO3 adds about 4.1 to 4.4 x as much K+ relative to N as a plant needs.
So roughly 75% or more of the N needs to come from fish waste before you might run into a deficiency of K+.
Note: adding a 3/4 teaspoon of K2SO4 after the water change will not hurt anything, but it will not help either.
High K+ has not been shown to cause issues in and of it's self, nor has NO3 in the 5-60ppm range near as anyone can tell or show from KNO3 dosing.
I've gone to 160ppm of NO3 using KNO3 without issue with the fish, I lost about 50% of the Amano shrimp after 3 days, but never lost one fish and all the fish later where fine from that short term exposure.
Long term chronic exposures at sublethal levels are extremely difficult to measure and do, aquarist are not equipped to measure that.
But many have used EI at full rates for many years and without issues.
So problems have not been apparent over several years both in my tanks and many others.
Regards,
Tom Barr