<a href=showthread.php?s=&postid=8480126#post8480126 target=_blank>Originally posted</a> by sjm817
It has everything to do with the discussion.
The bubbles created by the water flowing into the overflow collect at the top of a CPR overflow. This is why they REQUIRE a vacuum pump to remove them. If your CPR will flow the bubbles through the C Channel, you are incredibly fortunate, because they normally dont work that way. I've never seen or heard of one except for yours that will do that.
Without a vacuum pump, they will typically fail from air accumulation in 24- 48 hrs.
What exactly is your setup? What model overflow? How much flow are you putting through it? Maybe you stumbled on a setup that could be duplicated. I did notice on mine, low flow created less bubbles going through the weir, less accumulation, but it was always present.
I have 3 different CPR models on various tanks. At my office, I use CS100s on a 75 gallon and on a 45 bowfront. These never run for more than 6 months or so without me moving the tanks, it seems like. I set up the sumps the same way as my 180, though.
At home, on the 180, I use a CS202. I am not the original owner of the tank, but I set it up 5 years ago for a friend and coworker and did all the equipment work on it. i recently bought it from him because it had been in decline since Hurricane Wilma last year and he didn't have time to take care of it due to family concerns. I knew the tank like the back of my hand, so it was an easy choice to get it.
Right now, it's been three weeks since I broke the siphon because I needed to move the box from the side to the back to accomodate my new canopy. Prior to that, it ran for three weeks after a complete tank move. Prior to that, it ran for a little over three years without the siphon breaking. It was in a difficult spot to reach (a hole cut in a wall, between the living room and an aquarium closet, with metal shelves in the closet). The first time we ran it, using a wet dry instead of the current 40 gallon breeder for a sump, it ran for just a hair over two years (January 2001 until Valentine's 03, when he got the new sump as a present form his wife lol).
The only unusual part of the sump setup is the hoses. I use longer hoses than most people, so that the hose goes to the floor, curves up, and then goes over the sump to connect to plumbing on the top.
There is always an air pocket in each of the two overflow hoses, varying between 2 and 6 inches. The water flowing through the hose acts as if it is "filling up" the hose, closes the air bubble and then slowly goes down to it's maximum size again, then rushes to fill back up.
These air pockets are where all of the noise in the overflow come from. I occasionally adjust the "tubes" in each overflow bulkhead to quiet it down.
I don't think the length of the hoses has anything to do with the actual overflow, however. The original printout with instructions said to "pinch" the siphon tube closed. The instructions on the CPR site now say to use an aqualifter pump, a powerhead venturi, a check valve, or a gravity siphon. All of that is fine, but what works on the CPRs that I use is to put silicon around the air nipple, suck all the air out of the line, close the check valve, and spit the saltwater our of your mouth.
I guess I'm going to need to borrow a camera and take pics of this guy LOL
One thing I noticed is that I should probably replace the gang valve soon. It wasn't that corroded when i moved the tank here but now it's looking cruddy. It may be because I hung it on the side of the overflow instead of tossing it on top of the canopy. The old canopy was shorter and I didn't cut new lines because all I had was clear tubing and I prefer silicone for this. It is defginately cruddy now and if it corrodes out, I'll have leaks.
Also, Dan? I'm not brave enough to drill glass in a tank full of animals and possibly crack the glass when i have a reliable siphon. All of the local guys who have drilled tanks always say "I'll be glad to help but I'm not responsible if it cracks." That gives me the willies pretty bad.
