If the fixture is resting right on top of the tank that's a lot of light, I assume it is 4-54watt bulbs. According to THIS chart that would put you well into high light. Are you dosing any water column ferts & how long has the tank been setup? I think you may run into some algae issues with that much light & no CO2.
But to answer your question as to what foreground plant would suit your current setup I'd say moss because of the pool sand. Dwarf sags are nice low demand grassy foreground but in high light they tend to grow tall (they stay shorter in low light). Hair grass & pygmy chain swords would like your light but need a fairly rich substrate although people have had success with them without it but they are usually dosing water column ferts at least. Adding root tabs may be enough for them though. Blyxa japonica would look awesome in your tall tank but requires decent substrate and CO2 in most cases.