My hat's off to you. I love to see that you're trying to find out all you can about the proper way to build a pond, before you try and build one. Don't get me wrong here though..... Building a pond in your own yard, when you don't really know much if anything about how to properly construct one is perfectly fine. In fact, it's a great way to learn how to build one if you don't mind living with any mistakes you make. There's absolutely nothing wrong with it.
What I think is very wrong would be someone building a pond for a customer, when they don't have a thorough knowledge of what they're doing. You're definitely going about it in the right manner by trying to learn the right way to do it first.
I suppose it all depends upon the complexity of the project and what the pond is going to be used for, but I think it's wrong to agree to build a pond for someone that's going to pay you their hard earned money to do it, when you don't know if you're going to get everything right.
What prompted this response is the fact that I've gotten quite a few private messages lately that really amazed me. They actually scared me. No names will be mentioned here, but I will say this. If you don't know how to select a filter for the pond you intend to build for a customer and why you're selecting it. You're not ready to build ponds professionally yet. If you don't know what can cause an algae bloom, you're not ready to build ponds professionally yet.
You not only need to have the knowledge you'll need to properly build a pond for what the customer intends to use the pond for, but you need to be able to competently answer all of the common questions that a customer might ask you.
If I were you Laborador, I'd read a couple of the many books out there on the proper way to build a pond, instead of getting the video you mentioned. If you get a video like that, that's produced by a pond supply company. You're going to wind up getting biased information that might not necessarily be the best, most accurate info out there. You can find good, unbiased pond building books at Lowes, Home Depot, the library, or a book store. That's where I'd recommend you go to get your information.
Again Laborador....my hats off to you and all of the other guys on here that are trying to learn how to build these things the right way first, before sticking a shovel in dirt for money. That's exactly what Weatherman said he did and I commend him for it. That's the right way to do it.