Hi,
How can anybody say whether someones tank needs to be dosed or not just based their own tank? Unless the OP has exactly the same water, same routine, same stocking, same PAR and so forth, it's never a good idea to make these assumptions about another persons tank. Also, what does the size of the tank have to do with the price of coffee beans in Columbia? The plants have no idea what size tank they are in.
If anything, why not assume the opposite? Why not assume a tank should be dosed and then withdraw the nutrient loading if you can get away with it? Why wait for a deficiency and then have to clean it up? This makes no sense to me. I would rather try to avoid problems in the first place and not have to troubleshoot.
Barr's standard non-CO2 dosing goes something like this:
Add about 1/8 teaspoon of KNO3 per 20USG once a week or two.
Add about 1/32 teaspoon of KH2PO4 per 20USG once a week or two.
Add about 1/32 teaspoon Trace per 20USG once a week or two or, alternatively, about 1/4 teaspoon per 20USG of Seachem Equilibrium or other popular remineralizing agent once every week or two.
Cheers,