transducer and ff questions

Hey everybody I have a garmin echo 150 well my first question is how far down do I have to put the tranducer in the water? I had mines strapped to my rod holders which sits right above the water should I try and bring it down a lil more or is it fine there ... My second question is I'm having trouble adjusting the ff to get a clear pic i see the bottom clearly but the top and middle has a bunch of stuff in it that could possibly be trash?

That "trash" you are seeing could very well be fish. What does it look like?

Some looks like a lil cloud which I think are schools of bait fish and some looks like a bunch of little dots all over the screen I shoulda took a pic of it it would be more easy to explain how the pic looks

check the noise level settings

Most likely it's schools of bait fish. I have the echo 100, if it's too cloudy looking check your gain setting. I have mine set around 70% and it's cloudy but it gives good bottom detail
More gain you have the darker/cloudier the screen you will have.

For the transducer, you want the whole punk to be jn the water at all times.

Ok thanks I adjusted the gain to about 65 but I won't know how its gonna be until I get on the water ... Mines have a dual beam that I can switch over I guess one for shallow water and one for deep water but I don't know which khz would be better for shallow waters theirs a 77khz and a 200khz option

the daul is for bottom and side. you have a standard 60 degree cone down to the bottom but not sure what the side cone would be.