Which robot models are out there and have you had any experience with any of them?
Well, I'll relate my experience.
There are a bunch of robots available and many of them are identical...just "private labeled" to confuse the issue. I even found a website that showed all the robots and which ones were the same but I lost it and couldn't find it again.
So, even within robots, the more you are willing to pay, the more cleaning power and speed you get. I think the "Blue pearl" is about 750-800 or so (I really am guessing) and that should provide enough cleaning power for a 20x40 pool.
My pool is large and my first cleaner was a "little shark" (suction) for about $300 or so. He simply couldn't do the job....too much pool and too little cleaning power. That's not a knock against "Sharkie".....I think I would've gotten similar results with any cleaner in that range.
I recently bit the bullet and bought a blue diamond R/C for $1350 (Yikes!!
) but, to this point, it has been worth it. It cleans my pool in about 1.5 hours and, best of all, does so without me running my pool pump for the 10-12 hours I had to do when "Sharkie" was doing the cleaning.
Of all the robots, I think Aquabot sells more than anyone and they make them in several price ranges. Dolphin robots are probably next in sales volume. I've seen posted on this forum a couple of comments that folks think their Dolphins were built a little flimsily.
Anyway, you'll have to research them and figure out what makes sense for you. I will reeemphasize that my learning experience came to the conclusion that you pay for cleaning power.