NMPC for a simple tank

I tried to implement a NMPC for a simple tank system. Reference for the output variable (tank height) was say: 50 m, no matter how much I tried different combinations of prediction and control horizons and sample time, I couldn't achieve desired output (reference tracking).

Sample code:

% Init
nlobj_Tank = nlmpc(1,1,1);
nlobj_Tank.Model.StateFcn = @StateFunc_Tank;
Ts = 0.02;
nlobj_4Tank.Ts = Ts;
nlobj_4Tank.ControlHorizon = 2;
nlobj_4Tank.PredictionHorizon = 10;

% Validate
x0 = 10;
mv0 = 100;
validateFcns(nlobj_Tank, x0, mv0)

% Bounds
nlobj_Tank.ManipulatedVariables(1).Min = -1;
nlobj_Tank.ManipulatedVariables(1).Max = 800;
nlobj_Tank.ManipulatedVariables(1).RateMin = -0.1;
nlobj_Tank.ManipulatedVariables(1).RateMax = 100;
nlobj_4Tank.States(1).Min = 0;
nlobj_4Tank.States(1).Max = 1000;

% Actual plant model
Plant_state = @(x, u) StateFunc_4Tank(x, u) + 0.01*rand(1,1);
% Setpoint or Output reference
Out_ref = [50];
all_MV = zeros(25,1);
all_X_plant = zeros(25,1);
mv_now = mv0;
x_now = x0;
for i = 2:1:25
[mv_now, opt, info] = nlmpcmove(nlobj_Tank, x_now, mv_now, Out_ref);
all_MV(i,:) = mv_now;
x_now = Plant_state(x_now, mv_now);
all_X_plant(i,:) = x_now;
end

Code for tank: StateFunc_Tank;

%% Trying the single tank NMPC
z= zeros(1,1);
a=10;  %Area of the tank
R=0.1; %resistance of valve
%dh/dt = Fin - R sqrt(h)
z(1) = (1/a)*(u(1)-(R*sqrt(x(1))));

I am quite new for control and MPC implementation. Can somebody guide me how to implement a NMPC? What are the tuning parameters/ methodology to do the same? How to validate and visualize the NMPC results?

For MPC we have MPC desginer app and many tutorials but for NMPC I couldn't find any resources. Any help would be great.

Thanks