Bitbloxx BB vol filter

//@version=4
study(title="Bitbloxx BB vol filter", overlay=true)
length = input(15, minval=1)
mult = input(1.66, minval=0.001, maxval=50)
src = input(close, title="Source")
basis = sma(src, length)
dev = mult * stdev(src, length)
upper = basis + dev
lower = basis - dev
plot(basis, color=color.red)
p1 = plot(upper, color=color.blue)
p2 = plot(lower, color=color.blue)
fill(p1, p2)
avgvol48 = ema(volume,48)*close
longcond = (close<=lower)
cond1 = (avgvol48>=30000)

var sellLevel = 0.
if longcond
    sellLevel := close * 1.06
sellCondition = close > sellLevel
bgcolor(sellCondition ? color.red : na)
plot(sellLevel, "Sell Level", color.fuchsia, 2)

plotshape(cond1 and longcond, title="Long", style=shape.triangleup, location=location.belowbar , text= "BB" , color=color.black, size=size.small)
alertcondition(cond1 and longcond, "BB Long")