meh... still doesn't directly answer the question.
sears and conlin formula was a 1:1:2:1 formula by volume... with the 2 parts being k2so4. the formula the OP has is a 1:1:1:1 formula by weight.
seems to me to nearly match the sears and conlin formula he'd have to purchase a separate amount of k2so4. also seems to me that recent knowledge/wisdom suggests that with the dosing of kno3 and/or kh2po4, the extra k2so4 wouldn't be needed. if dosing both, it's likely none would be needed at all.
so 4 tbsp's seems to be right on par given the "formula" being used.
now to get some P in the mix. a little enema should do the trick given that k2so4 is in the mix already, no?
then he'd need a dosing calculator or a little math for P ppm's... https://www.plantedtank.net/forums/137172-post11.html
this may help clarify some of that... https://www.plantedtank.net/forums/241362-post14.html
here's chucks calculator... http://web.archive.org/web/200812170...t_aquacalc.htm
there are many others as well.
wet's calculator... http://calc.petalphile.com/
james' claculator... http://theplantedtank.co.uk/calculator.htm
and there's calculators on many planted tank sites and sites with planted tank sections.
for EI dosages, you'd shoot for 1-3ppm (or 1-6ppm for EI light [EI for dummies])
you can use my spreadsheet here for an easy reference if you'd like... http://www.filedropper.com/fleetenemadose
this one you put in your target dose in ppm and estimated water volume in your tank and it spits out how many ml's of fleet you'd need.
now he can discretely sneak some fleet enema off the shelf at any local pharmacy and have a "well rounded diet".
*that file will only be downloadable for 15 days and you'll need open office or libre office calc. both programs are free and open source. i made the file on a linux pc so, it should be virus free.
if ever the need for added N, he could pick up some salt peter. (green light stump remover or spectracide stump remover)
if i'm a little off here, feel free to straighten me out, tom.