Red Nesea

true jeff.. but for people who are just starting out and are scared to mess up, the liquid ferts are a breeze for them.. Plus if its a 10g tank im dosing the flourish bottles will last me anywhere from a year to 2+, thats what i meant cheaper for bigger tanks since you would have to use a larger volume.

The dry ferts are still a LOT cheaper.

If you can't get the dry ferts locally, then I agree it can be a hassle. But my hydro shop has a deal where I get dry ferts for magnesium, calcium, nitrogen, phosphorus, potassim, and micros(500g of each) for $25. Can you even buy the basic N/P/K/Micros in liquid for an aquarium for that much?
 
Are you talking about the liquid ferts lasting a year or two years based on their dosing instructions? I think those are insufficient; You'd need about 16ml to get 10g of water to 20ppm Potassium with Flourish Potassium. The dosing instructions tell you to use 5ml on 30g, or about 1.5ml on 10g.

A 250ml bottle lasting 2 years is 2.5ml a week. 2.5ml in a 10g aquarium is 4ppm. Not sure that's significant.

Dry ferts will last hundreds and hundreds of doses on a small(10g) tank when dosing to an appropriate concentration range.
 
AquariaCentral.com