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.

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.

air stone?

i don't have one of those

air stone?

i don't have one of those

There should be a line connected to the powerhead input with a piece you adjust for air intake.

theres sort of a thing with a nozzle and a dial, but i don't know how it works

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.

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.

no matter which way i turn the dial it doesn't seem to make a bit of difference. also nothing is collecting in the cup

Does the powerhead have a hose coming off of it? Where on the powerhead is this "nozzle"?

http://www.aquariumadvice.com/reviewpost/data/14/7686bakpakII-reef_b.jpg

It can take a week for a skimmer to break in and start producing skimmate.

i figured out why it wasn't producing bubbles. the nozzle was under water.

i is a moron

...

HAHAHAHAHA!

I'm not laughing at you. I'm laughing with you. That's pretty funny.

But yeah, the nozzle needs to be above water ;)

Bob,
If it helps any I have also had problems trying to figure out why my skimmer was not producing bubbles only to eventually discover the air intake was out of place and somewhere below the water surface.