I’ve never been a gate keeper of what I know and am happy to teach the customer as much about their equipment, water chemistry, etc. as they want. 
It’s easy for me to give too much info, too. 
I just do my best to read the person. If they’re engaged and asking questions, I’ll stay in it and answer what I can. 
I think there’s a vibe if they are interested or if it’s over their head and they’re fine with that. 
I think it builds trust to be open and transparent with knowledge and in some cases, lack of. 

I think you just have to feel it out. I also keep an open book policy. I’ll answer every question that comes up - especially at a first meeting. It usually gives the client a good sense that you’re on your game. Plus I think there’s almost always a natural point in the convo where they either feel satisfied with your competency or you’ve gone way over their head. They’re just glad to have you around at the point. With the Skimmer reports, they’re going to get most of the info they’d want to know regularly anyways. They mostly just want to know if you showed up or not. 

For repairs and installs, I usually like to provide 2-3 options with some basic points differentiated - my recommendation being at the top of the list (regardless of pricing being higher or lower). Makes it really simple and straightforward. If they have extra questions, they’ll usually ask. But it’s usually enough for them to feel like you’ve given them some thoughtful options. Plus it gives them a sense of control of the situation and not like you’re strong-arming them in a certain direction.

Hope that helps!

This may sound stupid, but I use a technique I have coined “the glaze over effect”.  For instance, if a customer asks me about pH in the pool and how we regulate it etc., I’ll start explaining to them that pH is an algorithm from 0-14, with 7 being true neutral, but we shoot for 7.2-7.4 even though that sacrifices some chlorine efficacy, etc

About 20-30 seconds into this I can see the customer usually has stopped listening and their eyes have started to glaze over.  I then stop and say something like “I’m sure this is boring to you.  I talk about it all the time because it’s the business I'm in.  But as far as the pH, my guys know what to do”.  They are almost always grateful that they don’t have to listen to me anymore and that’s that.  

Another benefit is that this establishes you as the professional when it comes to the pool and most people will willingly cede that authority to you even though they may have questions now and again.