What I do if I need water really quickly is use my kettle (bought for the sole use) to bring some RO to near boiling and add to my 25L drum. This warms the water very quickly.
The elements are made up of 80% nickel, 20% chromium - both of which you find in your common household taps, so quite...
Between 26 and 27 for me without a heater. My tank hit 34.8 during the really hot days this summer, with no adverse affects on the tank. Some of the corals sulked a little but perked up when the temp dropped.
My tank is next to the kitchen window and gets 4-5 hours of diect sunlight a day. Never had an algae issue in this tank. Excess nutrients cause algae issues not sunlight.
Urchins eating coraline is a good thing in my book, as the coraline covers the rock making it non porous after a while. So the urchins help out keeping the rocks porous.
Instead of removing and scrubbing the rocks in the display you can buy/rent a sea hare to start making light work on the algae. Then whilst it is doing that address the other factors as above.
You may be safer to drill the left tank and have it higher than the right tank (by a few inches) and let gravity do the work. Much safer than relying on a syphon.
I tried connecting two tanks side by side but could not get the fliw rate right until I raised one tank.