On the Spa-Daddy website, I did a search for a specific part number (Waterway 817-0131). The search provided two results- one regular and one microbrial and it was slightly cheaper than other websites. I placed my order which was promptly delivered. Unfortunately, the filters I received were short, for a different filter. They were NOT equivalent to the specified Waterway part number in the search. The very confusing thing is that a search for a specific part number provides a part which does not fit and is smaller than OEM. What I didn't notice at the time of order was that the correct equivalent was also listed, but I had to scroll way down to see it. Their return policy is fairly typical but I didn't want to deal with it.
One needs to be very careful with this website and know exactly what is needed. Don't rely on their search providing the most relevant part.
Spa-Daddy blames the manufacturer "a lot of the manufacturers do this multiple listing for their part numbers (Hayward and Pentair do 4 or more, all with different lengths), we list all the specs in our cart."
If you shop here, don't rely on a specific part number like you can on reputable websites.
By the way, do NOT believe the coupon websites which suggest coupon codes for Spa-Daddy. After purchase, I received an email saying they do not honor any discounts/coupons/promo codes, claiming those are all fake - first time that has happened to me. Feels like a third party bait to direct internet traffi to them.