Dolphin Sigma

I have owned lots of robotic pool cleaners over many years and was never completely happy with them. So 18 months ago I decided to buy the most expensive one on the market—I.e., the Dolphin Sigma unit. I am writing this review now to help the people who have been rating it with 1 star because the robot can get stuck on certain types of pool drain covers. I had that exact problem when I first installed the unit. I called the Maytonics customer service number and was able to speak to a human. That person explained that this issue happens with certain types of pool drains and offered a solution involving installation of an extra brush roller part on the bottom of the robot. Adding this part is akin to converting the unit from 2 wheel drive to 4 wheel drive. Maytronics provided me with an authorization to bring my unit to a local pool repair shop with the technical expertise to install the extra brush roller part, all at no extra charge to me because the unit was under warranty. I was very impressed with both the customer service response and the subsequent performance of my converted “4 wheel drive” robot. Now it never gets caught on my pool drains and it does a wonderful job climbing the pool walls and stairs with superior cleaning!