Having trouble with a Fluval Fx4

Jexnell

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I typically run two ac's per tank as well. What I do in this week rinse the left one and it's bag of bio-rings in used tank water during the water change. Next week rinse the right one. The sponge you can thoroughly rinse, the bio-rings I just flip them over a few times to get any gunk out.
 
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jjohnwm

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Try the simplest possible solutions first; in this case, that would mean making sure that the impeller and impeller chamber are clean. Any magnetically driven impeller can start to function intermittently or stop altogether if a piece of debris, or even too much biofilm growth, interferes with the rotation of the impeller. Cleaning them helps, and often with older pumps just tapping the impeller as mentioned by FahakaPapa FahakaPapa will get them going again. That's very simple with Aquaclear HOB filters; I'm assuming that with a canister filter, access is not as straightforward...everything is a PITA with canisters...:)
 

Jacky82020

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Sage advice & I think that‘s what I attempted, but perhaps debris etc was
left behind. The new impeller is out for delivery now by Amazon. Do you think it has to be either a bad motor or impeller? The hoses and all that are properly connected.
 

jjohnwm

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If you have methodically checked the entire flow path of the water and have found nothing...and sometimes it's embarrassingly easy to miss something extremely simple, like a closed valve, an airlocked bubble in the pump area or a dead fish in a hose :redface:...then it's pretty much guaranteed to be the impeller or the pump, and the impeller is the much more likely suspect.

If you are sure that it is clean, it costs nothing to simply pick the thing up while it's running, turn it upside down and give it a shake or two; if it's airlocked that might dislodge it.
 
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Jacky82020

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We even used an air compressor to blow through the hoses and end pieces. Nothing, I was at least hoping for an emerald or ruby, but got only air. Sure hope this new impeller does the trick. Continue to find it most odd the other FX4 works fine and the seller says both were up & running until the AM he took the setup apart for us. He says he’s totally mystified too. He said in a text a good smack might help. LOL. It did not. Maybe a time out in the basement.
 

caxcrew

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Oct 11, 2008
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We even used an air compressor to blow through the hoses and end pieces. Nothing, I was at least hoping for an emerald or ruby, but got only air. Sure hope this new impeller does the trick. Continue to find it most odd the other FX4 works fine and the seller says both were up & running until the AM he took the setup apart for us. He says he’s totally mystified too. He said in a text a good smack might help. LOL. It did not. Maybe a time out in the basement.
 

Trouser Bark

Dovii
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I have 11 FX6's working in my fish room today and have owned many of the other canisters available from various sizes and shapes of Eheim units (I've given up on that brand a decade ago) to several of the other commercially available units w/ pet store brand names. I standardized on Fluval about ten years ago.

A couple of comments about these filters in general would be that I have FX5's that are well over ten years old and still running the original impeller, motor, etc. and yes, they still flow at a high rate. If I were new to canister filters and couldn't figure out what the issue might be I'd first look to the seals. When someone sells their tank it's often the case that the tank's been broken down and dry for a while while they were figuring out whether or not to sell it.

That dry period is a problem as it dries out the big o-ring that seals the lid to the canister. I uses silicone grease made by Danco available for roughly five bucks at Home Depot to lube that gasket. The tube is small... maybe as long as your thumb but it lasts a long time. If I find myself in a pickle and don't have that grease handy I raid my wife's makeup drawer for some vaseline. It works like a charm you just want to make sure it doesn't have any contaminants in it from mascara or whatever they do w/ that stuff. Get that main o-ring lubed and then put a light film of the same lube inside the valves that connect the Fluval hoses to the lid of the canister. That "light film" aspect is important as you don't want to leave a bunch of extra lubricant spooged all over that gasket as you risk some of it eventually getting into other parts of your system... just moisten it. At that point fill the canister completely w/ water, open both valves and energize the unit.

There's a little bit of a knack to getting a canister to reliably re-start every time and after you've done it several times you may notice aspects that were causing grief before. The grief in my experience was that I was taking short cuts that were introducing a problem and once I knocked that nonsense off servicing my canisters seemed to get super reliable immediately.
 

kzimmerman

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Did you do a physical check of the impellor and motor? Look for scoring on the impellor or inside the motor. If theres physical damage, replace the units. If not, try soaking them in vinegar a bit to remove any hard water deposits and give it a good scrubbing. If that doesn't work, make sure that the shaft in the motor isn't bent, the ends are properly secured, and the impellor will freely turn by hand. I never had an impellor or motor go bad on anything except aquaclears. I have old whisper filters that still work from 25 years ago. SMH.
Sometimes motors that have been running for years have a hard time working once they have been stopped for a little while. A thorough cleaning is usually the answer.
 
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