jats:pWe describe new experiments in which particle-laden turbulent fountains with source Froude numbers jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline1" />jats:tex-math$20>Fr\_\{0\}>6$</jats:tex-math></jats:alternatives></jats:inline-formula> are produced when particle-laden fresh water is injected upwards into a reservoir filled with fresh water. We find that the ratio jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline2" />jats:tex-math$U$</jats:tex-math></jats:alternatives></jats:inline-formula> of the particle fall speed to the characteristic speed of the fountain determines whether the flow is analogous to a single-phase fountain (jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline3" />jats:tex-math$U\ll 1$</jats:tex-math></jats:alternatives></jats:inline-formula>) or becomes a fully separated flow (jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline4" />jats:tex-math$U⩾1$</jats:tex-math></jats:alternatives></jats:inline-formula>). In the single-phase limit, a fountain with momentum flux jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline5" />jats:tex-math$M$</jats:tex-math></jats:alternatives></jats:inline-formula> and buoyancy flux jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline6" />jats:tex-math$B$</jats:tex-math></jats:alternatives></jats:inline-formula> oscillates about the mean height, jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline7" />jats:tex-math$hm=(1.56\pm 0.04)M3/4B-1/2$</jats:tex-math></jats:alternatives></jats:inline-formula>, as fluid periodically cascades from the maximum height, jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline8" />jats:tex-math$ht=hm+\Delta h$</jats:tex-math></jats:alternatives></jats:inline-formula>, to the base of the tank. Experimental measurements of the speed jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline9" />jats:tex-math$u$</jats:tex-math></jats:alternatives></jats:inline-formula> and radius jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline10" />jats:tex-math$r$</jats:tex-math></jats:alternatives></jats:inline-formula> of the fountain at the mean height jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline11" />jats:tex-math$hm$</jats:tex-math></jats:alternatives></jats:inline-formula>, combined with the conservation of buoyancy, suggest that jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline12" />jats:tex-math$Fr(hm)=u(g\prime r)-1/2\approx 1$</jats:tex-math></jats:alternatives></jats:inline-formula>. Using these values, we find that the classical scaling for the frequency of the oscillations, jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline13" />jats:tex-math$\omega \sim BM-1$</jats:tex-math></jats:alternatives></jats:inline-formula>, is equivalent to the scaling jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline14" />jats:tex-math$u(hm)/r(hm)$</jats:tex-math></jats:alternatives></jats:inline-formula> for a fountain supplied at jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline15" />jats:tex-math$z=hm$</jats:tex-math></jats:alternatives></jats:inline-formula> with jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline16" />jats:tex-math$Fr=1$</jats:tex-math></jats:alternatives></jats:inline-formula> (Burridge & Hunt, jats:italicJ. Fluid Mech.</jats:italic>, vol. 728, 2013, pp. 91–119). This suggests that the oscillations are controlled in the upper part of the fountain where jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline17" />jats:tex-math$Fr⩽1$</jats:tex-math></jats:alternatives></jats:inline-formula>, and that they may be understood in terms of a balance between the upward supply of a growing dense particle cloud, at the height where jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline18" />jats:tex-math$Fr=1$</jats:tex-math></jats:alternatives></jats:inline-formula>, and the downward flow of this cloud. In contrast, in the separated flow regime, we find that particles do not reach the height at which jats:inline-formulajats:alternatives<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0022112016001671_inline19" />jats:tex-math$Fr=1$</jats:tex-math></jats:alternatives></jats:inline-formula>: instead, they are transported to the level at which the upward speed of the fountain fluid equals their fall speed. The particles then continuously sediment while the particle-free fountain fluid continues to rise slowly above the height of particle fallout, carried by its momentum.</jats:p>