Thursday, October 7, 2010

Step Fountain

On July 4th of the following year I began working on the mold for the next fountain.  This one was cast with ordinary concrete with a heavy cement to aggregate ratio.  In order to minimize cracking, the walls were made especially thick, and reinforcement was left out.

The pump was contained in the lower basin, and connected by rubber tube to the upper one.  The same lava rocks used in the two previous fountains were used in the bottoms of both pools.

Two problems showed up immediately.  The first was the apparent blow out of three sides of the upper basin (which upside down would be the deepest part of the mold - where pressure is greatest).

Because I wasn't all that skilled with a grinder I decided to leave the blowouts as they were.  The second problem was with the spill slot in the upper basin - it was too shallow.  The cast slot was only an inch deep.  Water pumped to the upper basin would fill it, and then overflow its outside edges.  I had to lower the edge of the slot, effectively enlarging it so that enough water could flow through to keep up with the pump.

This fountain, unlike the others which were on timers, ran all day, and all year.  I installed a 150-watt aquarium heater to prevent freezing.

Birds went crazy for it in the cold weather, and at least once we caught doves sleeping in it overnight - the water temperature was a warm 50 degrees, and the air temperature was in the single digits that night.  The birds stayed with just their heads above the surface.

This fountain lasted longer than the two that came before it, five years.  In its fifth winter, the heaters started to give me problems - they'd crack.  Replacement heaters, even ones meant for bird baths were of no help.  Birds would splash water out of the fountain during the day, the heater would be exposed, and when it was refilled, the cooler water shattered the hot glass of the heater.  The final winter, cracks appeared in the walls of the upper basin, where the concrete was only an inch thick.  By that summer, it could no longer hold water.

Winter view.  The heater keeps the water liquid and the snow at bay.

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