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Any spa can have some issues! Doesn't matter how much you pay or what brand it is, it might have a problem at some point. It's why you go with a reputable dealer, and a good company. Marquis is a great company, your dealer I don't know, as a company is only as good as it's dealer.
I know water chemistry and properly maintain my water at all times. These things aren't cheap and I don't have money to throw away. Also if it was something that I did I highly doubt that Marquis would have taken back my Euphoria and give me a heavily discounted price on a new Epic. I will say Marquis was good with that and my dealer was good at coming out and fixing problems. Sorry the OP asked for owners responses so I gave mine/chimed in. For the OP do a search on Marquis on this forum, other spa forums, the BBB, Google, etc. Also with on other spas that you are interested in. As I already stated, I hope you have better luck with yours than I had with mine. If you really love the Epic get it - just because I can't recommend it shouldn't stop you for getting something you want. Now if I were to listen to Tman I wouldn't have gotten my current spa that I really love!
Yes, I did get the Epic. It was the most comfortable tub I wet tested, and I loved the feel of the jets. The responses to my post helped me feel comfortable with my decision.