Question: Error, unable to convert to an explicit first-order system

Hello everyone, I'm trying to run a simple calculation (Water flowing out of a pressurised container) using a combination of conservation of energy and conservation of mass. I have working models of the same system without pressurisation (purely gravity working) which work fine in Maple, but when re-writing the pressure as a function of the height of the water I receive the error:

"Error, (in DEtools/convertsys) unable to convert to an explicit first-order system".

The formula used is:

"Eq1:= -Rho_Water * A_Barrell * v_Barrel = Rho_Water * A_Nozzle * v_Nozzle"

Which returns:

"Eq1:= -25.23733555 * d/dt h_Water(t) = 0.5982 * (-190.1309944 - 13.64385474 * h_Water(t) + (d/dt h_Water(t))²)^1/2"

With initial condition:

"ics1:= h_Water(0) = 0.2"

After giving the command:

"Sol1:= dsolve({Eq1, ics1}, numeric)"

Maple returns the aforementioned error. When trying to solve non-numerically the output is a list filled with "RootOf" and "_Z". Instinctively I would say the square root in the second part of the equation is the problem here, but I would not know how to fix this. Does anybody have a quick fix for this problem? Or is there a fundamental issue with the equation? Thank you in advance!