I am an attorney, and here is my perspective, and my personal approach with entering into these kinds of contracts.
First, find a reputable builder and get solid references, from people you know if possible. The idea is to have someone who will treat you right, so the contract never becomes an issue.
It is never a bad idea to have an attorney review a contract for a big purchase. That being said, there are different levels of review. Any good attorney can read a contract and find all kinds of little nooks and crannies where they would state things differently, add this, remove that, and make it the most perfect rock solid contract in the world that will protect and indemnify you from every eventuality. However, a small business pool builder is not going to react very well if you take this approach. Most will consider it an insult to their integrity and reputation they have worked hard to build. Also, they will see you as a lawsuit waiting to happen, and if I represented that builder, my recommendation as their attorney would be to find another pool to build.
The better approach, if I were you, is to have an attorney look it over just to make sure there is nothing really unfair or onerous in the contract. Most likely it will be (and should be) fairly boilerplate. If there is anything that really sticks out, it may indicate other potential issues with that builder, so rather than trying to redline it and negotiate the agreement, find another builder who doesn't have weird stuff in their contract.
Now my disclaimer: I don't know you, I do not represent you or anyone else on this site, and I am not even licensed to practice outside of California. Anything I say here is not to be taken as legal advice.