My Take on a DIY pool heater made out of black tube. Framework is two treated 2×4′s. Has 500′ of 1/2 inch black . that is tube Splitter feeds 200′ and 300′ of tube in two routes. I am going to feed it with 100′ of 3/4″ tube from the pool.
FYI, streaming considerably quicker than it’ll be when it is getting pool water and when I had it leaning against the shed it was likely requiring the temp up about 10 degrees from the faucet temp.