I've got a 125L with roughly 10 vallis, 10 cabomba and 2 anubias. I'm dosing 1.5ml of TPN and 1ml of Easycarbo....trying to follow the dosing for "lightly planted" aquariums.
Am I doing it wrong???
If you have a tank like yours with a few plants then just follow the instructions on the bottle. They are based on your 'average' planted tank and lo-tec setup. If you have a hi tec high plantmass setup then you have to up the anti.
Thats why most aquascapers (apart from those who have money to burn) mix their own because they would get through TPN+ almost as quickly as they get through beer

And in that scenario best to save the pennies so you can buy more beer instead.
If you are CO2 injected with decent lighting then go for the 1ml per 20ltrs. If you are non CO2 with lower light then follow the bottle (or even stop.)
As an example (and I will have to suggest the lighting level to you because being LED the WPG would suggest much lower levels of light than they actually produce.) When my 125ltr was high light (3WPG+ equivalent) and CO2 enriched I was dosing 5ml TPN+ (which I got for free) daily. Obviously when the bottle ran out I went back to dry ferts (EI and then PMDD+P.) When I went non CO2 I lowered the lighting levels (1.5-2WPG equivalent) and all I dose now is a pinch of KNO3 every month or so.
With the EasyCarbo I would suggest that unless you have an algae problem then follow the bottle. Unless your light is pretty high then it won't matter if the levels of C are low (remember it is liquid carbon and not liquid CO2.) Just as under a low light tank you can get by with equilibrium levels. The plants become C limited but that
shouldn't affect <2WPG tanks.
I should add that unless you are dosing EasyCarb due to an algae problem or that you want faster growth then it isn't needed at all in the <2WPG bracket (with a few exceptions - every system is slightly different)
AC