I agree with 2muttz suggestion to cycle your tank. I think any tank over2g should be cycled. It provides better water quality for your fish and, less important, it makes less work for you.
The Tetra 3i is worthless both as a filter and as a place for the bacteria colony. Lil's recommendation is excellent.
When cycling a small tank---or any tank for thay matter--- the operation can be made less stressful for you both if you keep close track of your water parameters (ammonia, nitite). Most of us use one of these.
[ame="http://www.amazon.com/API-Freshwater-Master-Test-Kit/dp/B000255NCI/ref=sr_1_1?ie=UTF8&qid=1379756505&sr=8-1&keywords=API+freshwater"]Amazon.com: API Freshwater Master Test Kit: Pet Supplies[/ame]
They last a long time and are always nice to have around.
It's also good to have Prime or some ammonia-detoxifying conditioner.
You've read the cycling stickies? So you have an idea how it works. Here's my one-sentence cycling tutorial:
Change half the water whenever the ammonia or nitrite rises to 0.25ppm, or weekly, whichever comes first, using Prime @2-drops/gal of tank capacity and 1-drop/gal daily during the cycle.
Last edited by Hallyx; 02-17-2014 at 08:31 AM.