There is something called autofill. I used that.
They say that it has a smart stop feature. What it means is if you don't change the chlorine part before it finished the water will stop getting filtered and overflow

. It makes a fucking mess
Also they say that they kill everything using chlorine. But if you keep it close to the sun you will see green color stuff growing inside the transparent compartment.
Cleaning it isn't easy if you aren't used to doing stuff like that at home. If you don't fit it properly there is a chance of the thing leaking.
Worst part is if you don't plan ahead to change it using their service you will have to wait for a few days for their technician to come and change it.
Not gona lie. Used it for around 3,4 years and just gave up. Too much of work machan.