Try better tube insulation and also there a big gap in the grill. Try covering it. A bigger copper heating coil should be also in consideration, or make two heating coils. Or ditch out the grill and make a large coil and put wood inside. No pump required for smaller pools.. Probably You would end up whit multiple insulated copper coils. Stacked car radiators should also do the trick like @mholiv said, but You should put the pump on higher speed so they wont start to boil inside. Be sure that the rubber hoses are high temperature proof. Or just put a thick steel barrel into the pool and put wood or coal inside, just make sure to add insulation on bottom so Your pool wont have a burned hole on the bottom.

I use a Moto G50 5G, my wife use a Moto e32s and most of folks in my work use some kind of Motorola phone. My work phone is also a cheaper Motorola. No dead pixels, charging time is fine, build quality is good. Updates could be pushed more often for the OS. IMO Moto phones are good budget devices, but I don't see where is the money flowing when buying flagship one. Like the Law of Diminishing Returns is cranked up to 110 for this company.