I bought the Sigma in April, and now its September and its a total loss. The Sigma started out ok, working fine for about 3 months. Sometimes it ran a couple times a week, and sometimes it ran 2-3 times a day, if there was a lot to cleanup or an algae bloom to work on.The Sigma started to break down when the runs started ending incomplete. It might run for 1 hour, or 30 minutes, or only 10 minutes at a time. I did all the maintenance checks: debris in the impeller and the track, making sure power supply was working, etc. I sent the Sigma to Maytronics to be repaired, and I had to cover the shipping, which was about $140. It was returned to me 2 weeks later. It worked at first, for about 2 weeks. Then, the same problems started happening again. The Sigma has completely stopped working now, it won't even try to start moving or spinning up.The Maytronics support is so poor. They don't respond to emails. I think I ought to get a refund or credit to replace with another device at least. Instead, I suspect I'm going to get nothing from Maytronics. This is the 3rd Dolphin cleaner I've owned in six years. The Premier was pretty good, it lasted me around 4 years. Then I had a cheaper model, I can't remember which one, which did a good job for 2 years. The Sigma seems to be a total dud. Maytronics took it off their website, they don't even sell it anymore. I think I know why.

I made the initial purchase of the Dolphin Premier through Terra Direct. The transaction was very smooth and shipping was quick. After running the Premier through its paces for almost a month, I wasn’t quite satisfied with the performance. It seldomly climbed the walls which is an important feature on my checklist. My pool is a 20k Pebble Tec with balanced chemistry. The pool was given a thorough brushing and it still will seldomly climb the walls. It also seemed sluggish moving around the pool. Filters were cleaned after each use (used the nano and standard fine filter). Didn’t have much use for the leaf filter although it has a very impressive capacity. After I gave the Premier what I thought was a fair chance, I reached out to Terra Direct for suggestions. They quickly responded and suggested the Dolphin Sigma which is considered an upgrade for the difference of around $100 USD at the time of writing. They confirmed there will be no restocking fee and the warranty is longer for the Sigma.After returning the Premier and receiving the Sigma, I immediately noticed a huge difference in power and cleaning capability with the extra commercial-grade motor. It also climbed the walls and did so very frequently and with much power. The app functions well and I mostly use it to manage the cleaning schedule or to start additional cleanings if needed. I tested the remote-controlled manual feature and it worked as expected (there’s latency, but it’s usable). I purposely didn’t brush a section of my pool wall to test the cleaning capability and I was satisfied to see how well the Sigma scrubbed the buildup. I was also impressed at how much dirt was captured in the nano filters. Accessing the filters is much easier vs the Premier since it’s top loaded on the Sigma. One thing to point out is if you’re using the nano filters, clean them after every use. If your pool is clean, you can get away with two passes max. Dirty nano filters will cause a significant pressure/suction drop and the Sigma will not climb or partially climb the walls. All you need is a garden hose with a spray nozzle and the dirt will be washed right off. It only takes about 5 minutes. Lifting the Sigma out of the water can be on the heavier side if you attempt to lift it directly out of the water but if you lift it to the top of the water, grab it by its handle, take advantage of the buoyancy and gradually let it drain before fully pulling it out of the water, it will make things easier. Lastly, it will not clean tanning ledges, although I’ve seen it climb stairs. You will still need to brush off the ledges and stairs but in the grand scheme of things, that labor is minor compared to the time and money you will spend on hired pool help. In summary, the Sigma has passed my critical expectations and I’m completely satisfied in this investment which will pay itself off in less than a year. But most importantly, the time saved and to be saved in the future is priceless. I hope this review gives you the confidence to purchase the Sigma and saves you time and possibly money with trial and error/restocking fees.

My pool was built 3 years ago and it came with a Pentair robot (not sure if this is a rebranded Dolphin, but I think it might be), and it has done ok, but finally just quit working entirely. The warranty was expired by 5 months, so I had to get a new one. I have had an old Roomba house vacuum, and if you've had one you know they just wander around aimlessly and they miss a lot of the floors. Then I got a newer robot home vacuum that maps out the house, and the difference was enormous. The new one does an excellent job, while the old one was just ok.That is the same difference between the pool robot that came with my pool versus the Dolphin Sigma.This thing is not just wandering around, it knows where it's been and it knows where it still needs to go. Not only that, but it scrubs the tile line, which the cheaper ones do not, and that is really important.I love that the app can schedule which days you want to clean and what time, and it notifies you when it finishes cleaning. I use the fine filters, and they always pick up a lot.When this thing finishes running, my pool looks great. I never need to sweep with this thing. It does it for me. It's not cheap, but it's the best. All the reviews I read pointed toward this one being the clear winner, the only exception is if you have a lot of leaves, the Premier might be better because it has a large bag to hold leaves. But I have no trees in my yard, so I get pine needles from the neighbors trees and whatever the wind blows in. But I didn't need the extra leaf storage, so I went with the Sigma. Also I don't think the Premier has wifi or an app.Anyway, if you are on the fence but you want the best pool vac on the market today, go for it. You won't be disappointed.