I would try baffeling the filters before you return them. I had to mess around with all my filters (2 aqueon quietflows and 2 tetra internal filters) as the flow is too strong.
I like the marineland ones because they have that biowheel which is where the majority of the bacterial will live and the wheel never gets replaced. Most other filters have cartridges that get replaced and when you toss them - you toss most of the bacteria with it. Anyways, for my Aqueon filters, I cut up foam for aquaclear filters and stuffed it where the water exits the filter. Then I added some plants in front of it to slow it down some more. I wanted to really slow the current as my tank is divided 3 ways and I didn't want the water flow to stress out the guy with the filter in his side. There is also a way to use a soda bottle to slow down the current. SOmewhere on this site is a sticky on how to do it.
I would hold off on the water change. You wont see nitrIte till you get ammonia and you need to have some ammonia in order to get the first wave of bacteria to move in.
What many put their fish through in the beginning without knowing about the cycle. Though it can be hard on fish, if you are diligent in water testing and performing water changes, you can get through it with your fish.
Pros: Well, not a preferable method of cycling. However it is fine if you have brought home fish without knowing about the cycle, just will take a little extra work on your part now. Done properly, lightly stocking a large tank, it will have minimal effects on hardy species (betta are generally considered hardy, however avoid this method if your fish seems sickly in any way).
Cons: High levels of toxins put fish under stress, and often cause death without proper action. You will have to perform many water changes and test water very frequently.
Process: So, fish have been added. They will produce the ammonia to get the cycle going. If you choose to do a fish in cycle, it is best to start with a small amount of fish in the tank to keep things under control. Doing 25% water changes whenever ammonia hits .25ppm is recommended. There will still be minute amounts of ammonia starting your bacterial colony, even after water changes. Eventually, nitrites will start showing up. Again, 25% water change whenever nitrites hit .25ppm. Once you start seeing nitrates, you know you have made it through the cycle with your fish! With the fish in cycle, you want to add fish slowly over the course of several weeks to your tank. Once your tank is fully stocked and everything is in order, you can start a regular water change schedule of 30-50% a week.
In 5gal-10gal filtered without live plants:
Water changes of twice weekly for the next 4-6 weeks
Of... 1-50% water only and 1-50% with vacuum in all areas you can reach without moving anything or disruption of plant roots.
*The 50% with vacuum will be the water change schedule for the life of the system to maintain water quality once the nitrogen cycle has established.
Filter media needs swish/rinse in old tank water a couple of time a month
*If you have water test kit-base the water only change on: ammonia, nitrite 0.25ppm or greater.
With a low bioload often you don't need the second water only-I always recommend it when you don't have test kit to err on the side of caution...its the safety net....
Live plants can change the cycling process as well, however, you have to