What I have noticed with BB with nifty is 3m TF seems to work well with 20,2 but for 5m TF it is too long. While 3mTF there is upper band piercing the 5m TF it is still in the lower band. Problem gets compounded with gap openings.
I think for 5m TF 9,2 might work well as Savantji said. However I find the in 5m TF there is a huge loss of info. So constantly looking a lower TF might be required.
The 2 consecutive green/red bar method works for 5m but not with 3m. Finding it difficult to figure out when to enter and exit.
LT,
YES,BB (20,2) on 3-min tf is very good.Just for trend, let us choose
5-min frame but 3-min for fine tuning .So always keep both 3 and 5 min
on your terminal side by side always.
If it is not bothering you can have BB(9,2) also ,but it touches the bands
frequently.
Don't expect to exploit market in both directions.To start with try with
one direction ,after fewdays ,you will be good at exploiting in both directions.