Tony for DHG you need a high PAR rating at the substrate. PAR is Photosynthetically Active Radiation. This is a measure of how much useable light there is for plant photosynthesis at a given distance from the light fitting. Basically it means how far light can penetrate through water. Even the worlds best light, the sun, can only penetrate through water so far. Hence why the bottom of oceans are dark.
DHG stays low to the substrate and therefore needs high PAR at substrate level.
Maybe a PAR rating of 50ish should be ok. So before you buy any lighting, you need to measure the distance from your light fixture to the substrate. Then contact the light manufacturer to find a PAR chart with given values for certain depths.
Remember with higher power lights there is a greater risk of algae blooms. CO2 helps to keep this at bay. As you move from low light to high light in your tank, pressurised CO2 will become a necessity to keep algae at bay.
Once your plants are producing food for themselves at a high rate due to the higher lighting levels they are going to use up more nutrients. This is where a regimented fertilising regime comes in, such as PPS pro or EI dosing. You can buy dry ferts and premix them yourself as they are much cheaper and a lot better.
The tank then becomes a balancing act. Light, CO2 and ferts need to be adjusted until you hit the sweet spot. This is when the plants will out compete algae for nutrients and you'll get an algae free tank.
High tech/light tanks are very interesting and hard work but the costs soon mount up. Dont look to rush into this. Do your research and take your time