Not sure of the dimensions of your tank but the standard dimensions of a 60cm are 60x30x36cm, which is 64L raw not counting the glass thickness.As I have a single 60cm tank, roughly 100 litres
Yes with only 1 tank it wouldn't make sense financially to do DIY other than being a nerd like me and knowing it is costing more than just buying a pre-made product, OR, because you want a specific mix that no other fert out there provides.so I'm using the spreadsheet for that purpose rather than to calculate how to DIY.
Indeed and that is on purpose: the manufacturer purposely omitted Mg for APT EI on the label. Secret recipe so it seems. How I know? I asked Dennis. In fact APT EI is in the calculator already but we have hidden it as it wouldn't make sense to show a partially complete product.IFC Fert Calculator includes APT Complete but not APT EI
I wont get into the details of the calculations you did (@Zeus. will probably answer the calculation part as he loves numbers, more than I do) as this would be nik-picking between APT Complete and APT EI (rebranded as APT 3 and APT e respectively BTW). Now, how to put this, the question you should be asking yourself is why you are choosing one fert over the other. Cost here is not really the factor as they are both the same price, granted not the same price per ppm of compound. APT Complete is a nitrate limited fert so are you looking for redder plants? If not then it would make sense to move to APT EI, otherwise stay with APT Complete.
Note that APT EI dosing quantities is different from APT Complete so with APT EI it's 14ml/100L/week if dosed daily, or 15ml/100L/week if dosed 3x a week. That's the recommended manufacturer dosing.
The Calculator also has a CostDetails sheet where you can see the price details and cost per major compound (Po4, K, Mg and Fe).
Note: I have actually been using APT complete for nearly a year now as I was carrying out some tests on that product. The only problem I see with that fert is it is low in phosphate and this has had the consequence of promoting GSA. I countered that by increasing the dosage to x1.5. GSA is now nearly completely gone.