Hi
I have the same issues water temp and cold at the bottom , i have changed the water temp probe which has fixed the temp fingers crossed the cold bottom after some digging seems to be the water pump ?
i have been told its low pressure which is why the water isn't circulating and heating the whole spar , ( water not pumping enough )
im looking for parts as i bought mine second hand and so have no warranty .
Ive had no help from Clever spar as they seem to be closed ? so ive been on you tube