What is a Volume indicator?
A volume indicator or a volatility indicator is essentially measuring the amount of movement in price in the candle. At its essence the ATR indicator could be called a volume indicator although it just provides us with a specific number of pips.
A volume/volatility indicator gives not only the measure of movement but also combines with another ingredient which gives us another trend signal.
The most popular volume indicator that No Nonsense Traders use is called the Waddah Attar Explosion (WAE) indicator.
It is made up of two indicators, Bollinger Bands indicator to measure the volatility/volume and a piece of the MACD indicator to measure the trend.
Please note that the above WAE indicator has many variants and modifications. I recommend trying everything you can find.
In conclusion finding a good volume indicator is part of the journey when creating your No Nonsense forex algorithm but after testing many different types I am confident that everyone can find a good one.