You have such a small pool without slopes and special form; you really can buy the cheapest robotic pool cleaner that can handle the waterline. To my knowledge, the Dolphin Proteus DX4 is one of the cheapest in the Dolphin brand.

I can recommend Dolphin Triton PS (or Plus—the same model but with Wi-Fi). It is very light and easy to handle, with a quick water-release function. It has an extra-large filter basket and superior filtering capabilities to keep your cocktail pool crystal clean.

I have Polaris EPIC 8642 iQ—the best model from Polaris! It has two modes: floor or floor/wall and waterline. With dual brushes in front and back, it cleans my pool perfectly. Its 4L filter canister size collects and captures all debris, including leaves and branches. You can control it remotely, and it also has easy lift removal.

I do not understand why you propose corded robotic cleaners. It does not make sense to have a robot with a cord! It is much easier to maintain your pool with Polaris Freedom Cordless Robotic Pool Cleaners. The price is the same, but you also have several cleaning modes, two retrieval methods, and a premium outdoor charging station.

Thank you for your question. These popular brands produce one of the best robotic pool cleaners on the market on each budget; we have a very useful detailed comparison of their best-selling models. As you need waterline cleaning, you need to purchase not a budget model. From Dolphin, I can recommend Dolphin Premier, Sigma, Quantum, Dolphin Proteus DX4, and Dolphin Nautilus Supreme. We have detailed reviews on all of them. Among Polaris, there are plenty of models as well – Polaris 9550, VRX, Freedom, Alpha, and Scout. All these models will handle your pool type and collect all debris. The difference between them is the price, navigation technology, size of the leaf bag, and ability to control remotely. I want to highlight Dolphin Nautilus Supreme and Polaris 9550 Sport, which have very good reviews and abilities to collect all types of debris in gunite pools.