Does anyone have any sort of rule of thumb or guidelines for at what depths they change frequencies of 2D DI SI?

I have a helix mega SI that I just installed.

 

I know the general rule is the deeper that water the lower the kHz but didn’t know if there is a depth people make that switch at.  TIA

Use the lower frequency which gives you a bigger cone to find what you’re looking for, then go back over it with the higher frequency to get better detail. 

Yup I know what each one does but more looking for depth ranges that people use each one for best results 

I'm with @12poundbass on this.  I change frequencies to change the cone angle sometimes.  There's very little water in my area that's deep enough to need lower frequency.  Especially for bass fishing.   I've certainly never had an issue in less than 75ft.

4 minutes ago, Tennessee Boy said:

There's very little water in my area that's deep enough to need lower frequency.  Especially for bass fishing.   I've certainly never had an issue in less than 75ft.

 

This ^^

 

Originally, the low frequencies were for things like Great Lakes “deep”, not bass fishing deep. As such, I never just go straight low frequency, but with most units, you can run split frequency and get some good benefits, especially with 2D. But in general, the higher the freq., the better the detail, which is why all the top end units are “Mega”-type frequencies.