On January 10, 2012:
I have 6 aquariums. I have used the Marineland Bio wheel filters. They are expensive to replace cartridges and always having to take apart for cleaning and repairs. I have replaced some with Tetra 40I and love them. They are super quiet; a fraction of the cost for cartridges (I make my own). I have two in a 55 gal. And two in a 45 gal. When I can afford them I am going to order 4 more for other tanks. The best inexpensive filter yet.

On September 15, 2011:
After installing my Tetra Whisper 40i, there is no top cap to cover the unit. I thought the top cover was missing, so I called and found out, there was no cap for it. So the whole unit put it inside the tank, just like trash can without cover. It looks like an uncompleted unit and ugly. The Function is ok, but if you care the look of your tank, do not purchase.

On November 8, 2010:
This works perfect for my 2 turtles I went overboard but it keeps it clean! And smells good!!!

On October 13, 2010:
I have been using tetra Whisper filters and bio-bags for years. I have an aquarium and I have a turtle tank with four turtles. I use 3 intank whisper filters in the turtle tank and they work great!

On June 24, 2010:
THE TETRA 40I IS THE BEST FILTER I EVER HAD . ITS VERY EASY TO CHANGE.

On April 20, 2010:
We bought the pf-40i & a pf-20i & for our 55 gallon tank. They are working great & are so... quiet. They are also great because they take up no space on the outside of tank.

On October 14, 2009:
I purchased this in tank filter after my regular filter leaked on my hardwood floor twice. Very quiet and seems to do a good job. Excellent filter for the price.

On June 20, 2008:
This is a great filter we use them on all our turtle tanks!

On November 23, 2007:
I have two Tetra Whisper 40i submersable filters and I love them. I have a 55gln aquarium with lush plant life and many beautiful fish and thanks to the Whisper 40i I am gettig better results in this aquarium than I have with any other filter product.
I definately recomend this submersable filter for anyone that wants great results for their aquarium and for a long life for their loveable fish buddies.
You have to have one...or two. Heck I'm ordering another one for my 29gln aquarium today.
:)

On July 27, 2007:
I purchased In-tank filter 101 and 401!
They prove excellent filtration for two tanks, one a 10 gallon and one 45 gallon which each house a turtle. Turtles put out a lot of waste and these filters work the BEST I have ever used. The ease in which I can change the filters is wonderful!

On May 6, 2007:
I left my bio-wheel filter in South Carolina when I came home for the summer, and needed a cheap filter. I bought this one, and discovered that it is just as effective as my biowheel. There is plenty of space for beneficial bacteria to grow, and it clears the water out BETTER than my Penguin filter. I was very suprised. I would recommend this to anyone. When I get my other filter back, I'm going to use both of them to keep the tank clean and extra healthy. An amazing and cheap filter - great for all fish.

On April 16, 2007:
I love this thing all I had to do is open the box put the cartridge in then plug it in. It was that easy it cleans great and quietly too. This filter is great for the money :)