Fluval C series is the best
The filter is crap. The motor is making a loud grinding noise and it is over flowing. I was very surprised because I've had aquaclears on my other tanks in the past. I will bring it back because I have a warranty on it and I will probably get the 50 or buy a tetra filter. I tried fixing the motor by putting some Vaseline in the impeller but it still makes the grinding sound.
I like the aquaclear filters for many reasons but one thing I hate most about them is the outflow. The outflow is placed near the top of the aquarium so you hear the loud water trickling sound. You will probably say fill the tank up more but if I do that the water will be right at the rim. I'm guessing the larger models have a deeper out flow so if I get the 50 instead of the 30 maybe it will be quieter. If that is not the case do you know any other good hob filters? I love the marineland bio wheels but the bio wheel makes to much noise even when the tank is filled up.
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I agree with the design flaws you dislike about the AquaClear.
I have an aquaclear 50 and a Fluval C3 running side by side on my 38 gallon tank and you would never know they were both Hagen Products.
The C3 is rated for tanks "up to 50 gallons" and has a 153 gallon per hour rating and the water flows from back to front in separate media compartments and 100% of the water is filtered with zero "overflow" until the filter gets dirty enough to clog and then it is easy to see the water to go directly into the tank without being filtered ... and the little "red button" starts popping up to let you know the filter is clogging. The mechanical compartment lets you insert cut to fit 5" x 5" x 1/12" inch 100 micron polishing pads for super crystal clear water. You cannot hear any splashing of the water and the flow causes no "air bubbles."
The AquaClear 50 is also rated for tanks "up to 50 gallons" with a 200 gallon per hour flow rate. However, it is easy to see that about 25% leaves straight to the outflow into the tank without being filtered unless you move the flow rate to the "low" setting. Although I got lucky with a silent motor on the AquaClear, I hate the splashing noise and those hideous little air bubbles that only go away if the tank is filled to where it almost overflows. I don't know how in the world you are suppose to know when the filter is dirty since the filter looked like it was clogged due to water flow right out of the box on Dec 27. You cannot use the 100 micron polishing pads because they restrict water flow too much.
[note: I am still running my Aqua-Tech 30-60 along side the AquaClear and the Fluval C3 until the AquaClear fully builds up with BB ... and yes, there is a lot of current going on in my 38 gallon tank}
I thought I had purchased a defective unit ..... and was ready to send it back ........ until I saw a "demo" on YouTube and it was running identical to mine. Further, there is no way to use 100 micron polishing pads because they restrict the flow too much so tightly packed floss will have to do. For those reasons, I got a C4 for my 29 gallon tank.
My AquaClear looks EXCATLY like this when it is running:
AquaClear 50 Review Part 2 - YouTube
Like the guy in the video, I use the pre-filter sponge on both filters.
I believe the AC 70 can be customized to provide much better filtration because it is a full 1and 1/2 inches deeper than the AC 50.