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Used CPR backpack

Mar 30, 2007
I have a few questions about a cpr backpack i got used. (don't worry the former owner had tube worms which would have been killed if there was copper in the system.) my question is whether the main chamber where the water is expelled and the big pipe is supposed to have anything in it.

also, what is the purpose of the grey thing on top of the intake chamber? it has no water in it. is the rubber intake tube supposed to be free floating?

theres also a bunch of foamy buildup on the top left over from when i put the sand in the tank, which is still very cloudy after a few hours.
Sep 8, 2006
As the water is sucked into the skimmer, along with air from the airstone, it will mix and create foam. The foam builds up in the top of the chamber and eventually builds up so much it is collected in the grey piece you are referring to. This is the junk you are removing from the water. Once the skimmer is running well and your tank has adjusted, you will find the collection cup fills with dark green/black goo. Yummy.

As for the other chamber, there is some filter floss (bio-bale on CPR's description) you can buy, or you could probably use bio-balls. Really there's not much purpose in that type of set up though.
Sep 8, 2006
You mess with that once the skimmer is running. It will increase or decrease the amount of air flowing into the intake chamber of your skimmer. This is the tricky part of using a skimmer. You don't want an excessive amount of air because with those HOB skimmers you're bound to have some excess bubbles going back into the tank, and it effects how well your skimmer works. You want just the right amount, so that the bubbles rise to the top of the intake and settle, and gather, and slowly fill the top so that they start rising up into the collection cup. BUT! Don't let them go crazy because they will overfill the cup REALLY FAST if you're not careful. Then you have a mess.

This is just something you're going to have to play with until you've achieved a good balance. The more you play with it, the better idea you'll have of how it works. Keep in mind, you don't need to use it until your tank has cycled and you have some kind of bio-load in your tank.
Oct 13, 2005
That's it. I also have a CPR.

You adjust the "nozzle" by turning it, to create more or less bubbles. I keep mine adjusted so that when I look at the whole thing from the side, I can't see through it, there are so many bubbles.

Don't be too sure about the copper. I used copper in my reef tank (long ago...) and I still have tubeworms, pods, corals, inverts, etc.

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