Bubbler
Also called: geyser jet, ledge bubbler, pool bubbler.
A bubbler is a pool water feature that sends an upward burst of water in shallow water. Bubblers are almost always installed in 6 to 12 inches of water, which is why a tanning ledge is their natural home and the two are usually one decision.
Why it matters
The bubbler is the value pick among water features: cheap, quiet, low-flow, and safe around children playing on the ledge. Flow is low enough that owners report running one at low RPM on a variable-speed pump, and a valved line off the existing system is normally enough. It is also the quietest feature and the closest to the sound category that tested best. A bubbler aerates, so it pushes pH up without changing total alkalinity, and experienced owners run one on purpose to bring pH back up after adding acid. On a pool without a shallow shelf it is not a retrofit at all.
In numbers
A bubbler spec quoted on Trouble Free Pool puts demand at 17 GPM for a 1/2-inch nozzle and 31 GPM for a 3/4-inch nozzle, so going up a nozzle size nearly doubles the flow.