the digi would have to be all the way at the top...i would stay away from anything besides a digi for sps...and they need to be kept high in the tank.....the t5 lighting in the nano's is not equal to the t5 from a tecklighting fixture...That is an excellent size tank as well, if he ever wants to add MH fixture to it he can....Mushrooms grow like weeds aka no no....i would say frogspawn bam bam zoas(slow growers)..nothing really grows slow in a mature tank? Define a time period and we could help....