Protein Skimmer for 40g

[Schnertzel]

I'm a novice and have a very basic 40 gallon reef tank set up with some coral frags, 4 small fish, 2 urchins, 2 conches, and a smattering of snails and hermit crabs. Up until this point, the only equipment in/on the tank is a heater, lighting, and a hob Marineland filter with carbon media. I would like to add a protein skimmer to the tank, but I'm having a difficult time determining which one to purchase. I'd like to get one that is effective, but would prefer not to spend a fortune. I'm also concerned about the amount of space it will take up in the tank, as I don't have a sump to put one in.

Advice, please?

[phobos2deimos]

Without a sump, your choices are limited to the very narrow selection of hang-on-back units. I had a CPR BakPak and it was almost useless for me. Switched to a sump and installed the $95 SCA 101 (http://www.amazon.com/SCA-301-Gallon-Protein-Skimmer-Sump/dp/B00CML49CK) and was very pleased. Eventually went witha macro-heavy fuge and display and removed my skimmer altogether.

[Jade5051]

There are a few of good options out there. I'd probably get something used. These are skimmers that I see used consistently with good ratings.

AquaC remora try to get the pro or S model or the Pro S model. The skimmer boxer is suppose to increase their performance quite a bit.

Eshopps PSK75H

AquaMaxx HOB-1 Hang-On-Back Protein Skimmer

JNS Ice Cyclone Hang-On Needle Wheel Protein Skimmer - VS-1 (same as the aquamaxx just cheaper)

Reef Octopus Classic 100 HOB Protein Skimmer