Back to the original question: "if I could just dump water into the snorkel I could then just use an air lift pump saving on the electric bill each month."
Does it matter whether you add water to the top of your snorkel or to a pipe coming from a pump that is sitting in your pond? No. You need pressure to force the water through your gravel. With a clean (new) bog with large cross-sectional area, the required pressure is nearly nil. But let's assume that there's a little bit of dirt and/or that the bog isn't that large. We'll measure the pressure required in vertical inches of water -- how tall a water column would you need to push the water through. Let's say it is a hair under 2". That means that if you dump water into the top of your cleanup pipe, you'll need to raise the level of water in the pipe by 2" (2" above the bog surface level) in order get water to flow. Another way to view that is that as you add water to the snorkel, the level will not drop below 2" above the bog. So now your pump, whether magflo or airlift or small child with a bucket, has to lift the water from the pond 2" in order to get the water to flow: the "head" for the pump is 2".
If you instead use a pump somewhere in the pond and pump water directly into the bottom of the bog, you have to do exactly that same amount of work -- 2" of head. (Pascal's law.)
So from that analysis, you do not gain anything by putting the water into the snorkel versus directly into the bottom of the pond. Of course, I am ignoring the resistance of the pipe that you use to pump the water in. The snorkel is likely very wide, so it contributes essentially no resistance. The pipe, on the other hand, will add resistance, depending on internal diameter and flow rate. Typical values are 6' per 100' of pipe (1.5" pipe @ 1800 gph, 2" @ 3600 gph, 3" @ 10,000 mph). (Google "friction loss (in feet of head) per 100' of pipe") Bends in the pipe, especially right angle bends, add still more resistance. So the snorkel saves on that. BUT - you don't want to scoop your water off the top of the bog, so you still need piping to bring the water in from the pond. Bottom line (pun intended) -- I think you'll find that putting the water into the snorkel, versus pumping it "directly" into the pond bottom, are essentially equivalent.
By the way, I thought that DC pumps would save me a whole lot of $. I have a 40,000 gallon pond with an 9000 gph pump going into a 13x13' bog. That's 800 watts, about 7 Mwh/year, which at 15 cents a kilowatt hour is $1000 a year! Ouch! With a DC pump I can cut that in half. But AC pumps typically are relatively insensitive to small amounts of head - mine generates 30' or more of head and flow drops maybe 10% with 5' of head. A DC pump, on the other hand, will often only generate 5'-10' of head, and flow is proportional to head. A DC pump that generates 10' of head will typically generate half its rated flow with 5' of head. Check the specs before you buy!
larry
