Overflow priming

[drummerboy]

Ok, maybe I'm stupid, but I bought an overflow from a lfs, who has a friend that makes them. It's an exact copy of the new cpr's except for the air

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to hook up a power head. I can do that easily enough myself. My question is how do you prime it? Just set it in the tank, put water in the back of it, and when you let it all flow out the bottom does it automatically prime itself? I hope the guy built it right. He works at an acrylic shop, and has it all formed and stuff. It's just that I got it for $20 rather than $99. Pretty good deal, even if I do have to monkey around with it. Sorry for the dumb long question, but I'm just not getting it to work.

 

[broomer5]

Get yourself a length of airline tubing, 3-4 feet long works pretty good.
Return pump off - obviously.
Fill the outer box until the water stops running down the drain. A properly designed overflow will allow some water to remain in the outer box.
Pour some water in the inner box too.
Place the siphon tube in the overflow. There must be water covering both open ends of the siphon tube. Must.
If so, remove the siphon tube again and slip one end of this airline into the siphon, and push it up there until it's open end is just a little past the highest point of the siphon tube.
Hold everything so it doesn't move around on you, and return the siphon tube to the overflow.
Both ends of the siphon are now under water with this airline hanging out a couple feet.
Slide the airline out a little so the end that's in the siphon is at the HIGHEST point in the U tube siphon.
Now - suck the air out of the siphon tube by sucking on the airline with your mouth.
You'll notice as you draw the air out, that the water in both inner and outer box begins to raise up in the U tube. When you get all the air out, pinch off the airline tubing with your fingers and pull it out of the siphon tube.
Keep the airline pinched off while you're doing this or air will rush back in through the airline tubing and you'll lose some of the water in the siphon tube.
Once the U tube is filled - you have now "primed" the siphon, and it should be safe to turn on your pump.
If this is your first time doing this, you may want a couple few gallons of saltwater mixed up on hand. You may notice a small drop in your sump or wet/dry, and will need to add some more water. How much all depends on each person's set up.

 

[uncle fester]

If the overflow is a true copy of the cpr one I had, you need to install that

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! Once installed and water in outer chamber, suction at that

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via airline hose will begin the siphon. The return pump idea worked well for me, I installed it in my sump and ran airline tubing to

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. Make sure this pump is strong enough that the "venturi" or aerator can pull hard enough to start the siphon. I used a (hagen?) 402 for mine, worked great.