Oh, if it's going to be a brackish tank, HC won't work, the leaves will turn yellow pretty quickly. Glosso is another plant that will give you that carpet effect and will work in brackish water, it won't pearl as much as HC under a good light, but you'll still get some bubbles going. The dwarf hairgrass will also work, it will not have a problem.
Most of these will work in brackish water as well:
Banana plant, cryptocoryne ciliata, glosso, anacharis, common milfoil, hornwort, moneywort, microsword, java fern and java moss.