Riccia can be an extremely fast grower and produce lots of oxygen bubbles under the right conditions. You need high light (I am using two 36 W PLL tubes on my 2 foot tank, thats 4+ Watts per gallon), CO2 and maintain adequate fertilizer levels. I am dosing something like 10 - 15 ppm of NO3 and 1 - 1.5 ppm of PO4 daily on this tank.

Maintenance is to trim the top once in a while to ensure they don't get too long. Since they are quite dense, they have less of a tendency to break away. If you want thick riccia mats, make sure you weigh it down with something substantial... some of mine are ready to take off, mesh, pebbles and all!

Algae will also grow in between the riccia so you have to monitor the situation so it does not get out of hand.