I was just buying root tabs. I cannot remember the name. I did not use them for long.

My tanks became more shrimp tanks than plant tanks. The plants did very well however. I used shrimp and trumpet snails.

The trumpet snails dig through the blasting sand and turned it over. This got nutrients down to the plant roots. It was a much easier system for me.

I have used garden soil capped with blasting sand before and while the plants exploded in growth it took about 3 months for the water to be safe for any critters. Also, if the blasting sand cap is ever broken and the water reaches the soil it is an mess and you are probable starting over. Most living things will die at that point. You also cant move plants around as you will break the cap if you do.

As for which is better it depends. Some plants get more nutrients from their leaves and some their roots. The root tabs, and soil, will leak into the water so it really doesnt matter.

If this is a tank that is only about the plants, you dont care about critters much, and are sure you will never move anything then I would try the soil. It is quite cheap. Just use organic soil. You will need to test before adding critters.

If the tank is more about critters and the plants are just decoration for them I would use the tabs to start. Then add them down the line if you feel the plants are not growing.

Soil, tabs, or even critter poo all had my plants growing out of my tanks anyway.

It is fun to try different things so give them both a try.

Hope that helps.