diff --git a/src/tankdemo.jl b/src/tankdemo.jl
index 616082afcc3707bb68d8207521c235eba59f25fe..75ba50393fbdd2fd4b39736e3bcc4d46db5ada21 100644
--- a/src/tankdemo.jl
+++ b/src/tankdemo.jl
@@ -31,7 +31,7 @@ function runprocess(;simulated=false, webservice=true, port=8000, σ = 0.001, du
         n = 1
         LabProcesses.initialize(P)
         start_time = time()
-        for t in 0:P.h:20
+        for t in 0:P.h:duration
             y  = measure(P)[n]
             r = gui[:r]
             if gui[:tankno]=="Upper"