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HOB Filter Issue


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I have been doing a fish-in cycle for 3 weeks now. Just now I noticed one of the 2 HOB filters I have running (aqua-tech 10-20) has water falling out the wrong side. I also noticed the out has much less flow than usual. I even usually attach a cut water bottle to the end. This is my first 3 weeks ever with fish. I assume I need to clean the filter cartridge and that is causing a backup of water. What worries me is losing much needed bacteria during a fish-in cycle. 


Sorry the pics might not help the best. I tried to attach a video but couldn't. 


Is that what's wrong with the filter?

What's my best course of action?



Edited by Cinnebuns
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First off, your cartridge looks caked with debris, so I'd clean it with some old tank water to keep the bacteria alive until you can get a good cycle started. 

Secondly, cartridges are a scam. After you get your cycle started and running smoothly, I would recommend picking up some filter sponge. Like the image attached. This way, you can save money and build your bacteria on a good media that doesnt have to be replaced every month or ever really. 

Thirdly, it looks like you got a glow tank getting started with a tetra, I can already tell that this is gonna look nice. image.png.94c9ff964604e81868d22a67c9575eed.png 

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On 12/14/2021 at 1:14 AM, Keeg said:

your cartridge looks caked with debris, so I'd clean it with some old tank water to keep the bacteria alive until you can get a good cycle started.

I second this. HOBs have an over-flow because when the filter media is clogged the water level rises. If it gets too bad it might run off the back and onto your floors. If cleaning it doesn't work well enough and the water level continues to rise you might want you toss it even with the extending of your cycle just to prevent a potential mess.



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I noticed in your fist picture that you have a power cord in contact with the filter housing.  Cord placement should be watched carefully.  Even a trickle of "water falling out the wrong side" of your HOB could find that cord and potentially follow it out of the aquarium, leading to a flood or worse.   ...Speaking from experience

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Here is how I have mine setup.

I left the Bio plastic filter in and put a floss pad behind it with a couple of aquarium safe pot scrubbers.

Experimentally, I also put floss on the right side just to see if it will filter anything.

Your other option is to put a sponge in place of where I have the bio plastic, pink floss, and pot scrubbers.

You will also find a Aquarium Co-op video on how to "hot rod" a HOB filter.  


Here is the video I mentioned above.


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@Cinnebuns; Aqua Tech HOB filters are great, I have several, they're made by Marineland and are sold at Wally World under the Wally World brand name, instead of "Great Value" they're sold under the name "Aqua Tech". I have two 10-20s' that I've been using for about 15 years, I have a 20-40 and a 30-60 that have never been used yet.

Marineland changed the design of their Aqua Tech HOB filters and yours is the newer design, I bought a newer design Aqua Tech 10-20 just so I could bring it home and check it out at my leisure. The only thing I didn't like is the design of the intake strainer, it wouldn't accommodate my existing pre-filter unless I take the strainer off, which is no problem.

If the water is coming out of the back of your filter, check for cracks in the filter housing, if it's going over the top, remove your activated carbon cartridge and throw it away, you don't need it. Instead, you can buy a block of Fluval filter foam and cut a piece to fit behind where the activated carbon now sits. If and when this gets dirty, you can remove it, rinse it off in running water, place it back in the filter and you're good to go.  Never throw the filter foam away, this is where the majority of your beneficial bacteria will grow.

If the water is coming out the front of your aquarium, consider raising your water level so you don't have a waterfall effect, the waterfall effect produces drops of water that can splash everywhere. Your power cord runs from the filter over the top of your tank, and I can see drops of water on the cord. Remove your power cord away from the top of your tank and around to the back, yours is dangerous as it is now.

A filter is most efficient if it creates a vortex in your tank to push the mess in the front of the tank to the back of the tank where the filter can pick it up and remove it. Raise the water level to the point that the top of the water is at the bottom of the lip of your tank where a hood or glass top would rest on. When you do, you're going to immediately see the effects of that vortex, you'll see gunk being pushed to the back of your tank and may even see your filter take it in.

This is your first aquarium, you're going to make mistakes, we've all made them and are still making them, we try to learn from our mistakes. You've entered into a great hobby, one that I hope you will enjoy for a very long time as I have. 

Welcome to the forum.



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