Hydrilla uses indirect bicarb and Egeria is similar.
Pondweeds do, Stuckenia and Potamogeton etc.
Maberley(1983) and Madsen have decent papers of the topic.
Milfoils do also.
The bicarb is used only when a threshold of lower CO2 in no longer available or a good trade offs, then the plant switches to HCO3 use.
So.......if you want to increase growth, simply add CO2 gas, in nature, the plants have to make do and get whatever is available to gain an advantage vs another aquatic weed. So C4 metabolism and CAM even......as well as bicarbonate use when the CO2 gets low are all viable advantages. A small change in acquiring carbon over time can translate into huge gains in biomass over a year or more.
You might read pages 6-9 or so.