moss carpets can be quite messy.
crypt parva is a slow grower.
baby tears/hemianthus micranthemoides need a bit of light to hug the substrate. dwarf baby tears/hemianthus calitrichoides needs a pretty fine substrate and decent light to the bottom of the tank. many folks need co2 for it too.
riccia will be quite the mess everywhere unless you're diligent with keeping it rounded up. it doesn't root/attach to anything, each plant is only one tiny/thin leaf and it will constantly float to the surface, in the current, etc..
dwarf hairgrass gets quite tall and will need trimming to control height in a smaller tank.
these are the negatives of each plant as i see them. if this is definitely the group you want to choose from, i'd suggest choosing the lesser of the evils.
for example;
if you can find/afford enough crypt parva to cover ~1/2 the area your looking for densely and you want low maintenance, it's a great option.
if you like fussing over your tank every day and just want something to cover quickly then riccia is a good option. get it, float it until it's adjusted to your water and dense enough to cover most of the area you need, tie it on to some knitting canvas and sink the whole matt using rocks as anchors at the corners.
i would suggest... with all of these... if you're not so confident how they'll grow for you... to put a small, makeshift terrarium together to grow a bit terrestrially on the side. this way, if it doesn't work out in your tank you still have some later to try again once you get a better hang of things. just keep the soil wet and the terrarium covered to keep the humidity up and they'll all grow quite healthy and like the weeds they are.
warning: if you try terrestrial growth... hm, hc and riccia will all look like they're dying for the first couple weeks if they came from aquatic growth. DON'T LET THIS FOOL YOU! if they're kept moist and humid they'll come back with a vengeance in no time and grow like mad.
here you can see crypt parva, red root floater and riccia growing emersed...
here's a closer look...
here you can see hm (baby tears) and hydrocotyle sibthorpioides growing...
here you can see glossotigma elatinoides on the first "shelf"... behind ficus pumilia 'rikke'
there's also a little hc and bolbitis fern growing in there. :dance2:
