Danny D. wrote:
Have you ever dealt with a dirty water pump that just wouldn't
drain the last few inches? Is there a simple solution?

I bought a 1 HP Harbor Freight 69300 dirty water pump to drain
a green pool but it won't turn on at low water levels:
https://c2.staticflickr.com/6/5458/1...ee73cc98_c.jpg

Even with the obnoxious float switch manually set to permanent on,
the pump stops pumping with plenty of dirty water left to pump out:
https://c4.staticflickr.com/8/7699/1...45741c9b_c.jpg

I'm currently shoveling the water into a garbage can and then
pumping it out from the garbage can:
https://c1.staticflickr.com/9/8811/1...f798a613_c.jpg

But, pumping at 50 gallons per minute, I have to constantly run
to the GCFI and pull the plug to shut it off before the garbage
can runs dry:
https://c4.staticflickr.com/8/7642/1...c37715ab_c.jpg


The pump probably stops pumping when it starts drawing air. So, you need to keep
air away from the input. I can suggest a couple possible solutions.

1. Take a sheet of bubble wrap, or maybe just plastic sheet, maybe 3 feet square
at the minimum. Cut a hole in it to fit it to the pump just below the outlet
tube. Tape or caulk it to the pump to eliminate air. Place the pump in the
water, and place suitable boards, bricks, rocks under the plastic to maintain a
water path to the pump, tapering towards the edge of the sheet to maybe 1/4"
above the pool bottom. Thus, you have a long thin path for water to reach the
pump in sufficient volume. The edge of the sheet will need to be weighted down
to hold it on the spacers. A hard plastic layer under the plastic sheet could
help keep it from collapsing between the spacers.

The outer edge spacers could be narrow strips of corrugated plastic which is
made like corrugated plastic, and is most commonly seen used for political
campaign signs. Water would pass through the corrugations.

2. drill a bunch of holes in the bottom of a barrel, or even a plastic bucket
deep enough to hold the whole pump. Keep the holes in from the edge of the
bottom to reduce air whirlpools from reaching under. Place it in the water on
some pea gravel to allow water to reach the holes. Place the pump in the
barrel, Add a top with two holes, one for the outlet hose, sealed around the
hose. The other, for your shop vac inlet. Attach the shop vac and turn it on. It
will draw water into the barrel high enough to cover the pump. Then, turn on the
pump. If the pump draws water too fast, either drill more holes, or use a valve
to restrict outflow from the pump outlet.hose.

When you start the pump. if air under the plastic keeps it from pumping, use
your shop vac at the end of the outlet hose to draw the air out, and the pump
should start pumping. Remove the vac before the water gets to it.

3. There are actually shop vac's available with pumps built into them. I don't
know how high they can pump.