They're superb filters. Be carefull to put the exact measured amount of powder in. They're a little fussy if you go too much or too little.

Get the carbon. You can get utterly crystal cleat water if you use their carbon as well. If you can't find (or afford) their finely powered carbon you can make it by taking any high grade activated carbon and passing it through a blade type coffee grinder. This is actually a recommended technique for cleaning such a grinder as the carbon is harmless. Spouses of aquarists are seldom convinced of this though and sometimes it's better to pick one up in a thrisft shop just for this use. Store it in a tightly sealed glass jar, "spice" jars are good for this.

Once you get a handle on it and have learned the black art of quieting the beast down it's not too noise inasmuch as you can call it's quiescent state "quiet".

Some bubbles are normel, and if not, inevitable.

I only get absolute oh-my-God crystal clear water from it in two ways: let it run for 12-24 hours to get EVERY BIT of stuff out of the water or use carbon for 4 hours. It's usually noticably improved in 30-60 minutes

They get hot. Quite hot. Normal.