# Sunsun canister flow problems?



## WaterLife (Jul 1, 2015)

I'm thinking you probably still had a bunch of air trapped in the canister filter?
Use the priming button to purge air out and start a siphon. Once you plug it in and get it running, tilt the canister filter front, back and side to side to let the air pockets flow out.


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## Immortal1 (Feb 18, 2015)

One thing that effected my Marineland filter was the pump head to canister seal was leaking vacuum. Replacing the seal helped a lot.


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## jamielands (Jun 22, 2015)

I checked for air. I primed, tilted, primed again, tilted more...ill do it some more to be sure. 

I'll try to look into the seal tomorrow, see if there's anything to that. 

I can't imagine what changed! I'm watching tiny bits of debris float leisurely around the intake and occasionally maybe slowly float into it. And the fish are swimming through the outflow as if it's nothing. Before cleaning yesterday it was fine. 


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## thedood (May 30, 2015)

If I might make a suggestion. Try rubbing vaseline or silicon grease around the head seal and reassemble. Make sure its primed and burped well. If that helps I would order a spare seal or two.


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## jamielands (Jun 22, 2015)

Ok, I'll try that tomorrow as well. 

Would the fluval be better in the long run? I already bought it online, it's coming on Wednesday. I could keep the sun sun as a backup. I'm not sure if I should return the new one or just keep it and switch. I kind of bought it in a fit of rage after screwing with the sun sun all day and an hour or two of futile googling canister filters


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## Nlewis (Dec 1, 2015)

Did you make sure you put the motor head and trays back in the same direction? I know these are basically knock off Marineland filters. On my C-series there are arrows on all the trays and the housing.


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## jamielands (Jun 22, 2015)

Nlewis said:


> Did you make sure you put the motor head and trays back in the same direction? I know these are basically knock off Marineland filters. On my C-series there are arrows on all the trays and the housing.




Yes and no. I have seen previously in a video that some of them have a little circle on the bottom of the canister to show you where to align the holes on the trays. I took them all out and turned them around be other way to see if I had them wrong, no change. I still have no idea which way is right or if it matters. 


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## Lonestarbandit (Feb 7, 2013)

I don't mean to sound insulting but I have done all of these things myself...
1. One of the baskets are positioned wrong.
2. The distribution block is on backwards.
3. Hoses are kinked somewhere.

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## WaterLife (Jul 1, 2015)

Do you see air pockets in the green tubes?

I've had two SunSun canister filters that both had a little pin hole in the black plastic tubing that has the adjustable leveler (ribbed/grooved) for the surface skimmer attachment, so if the water level was below that hole (or if you have a hole/air/vacuum leak anywhere for that matter), leaving that hole exposed, air would be sucked in, constantly filling the canister head with air.

As for the UV hole alignment, just as long as the canister head mounts correctly (latches on correct sides, which in turn the UV will line up with baskets properly) it's fine.


If by chance you removed the hoses from the fittings, maybe you re-attached the inlet tube to the outlet quick release side (or vice versa).


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## jamielands (Jun 22, 2015)

Lonestarbandit said:


> I don't mean to sound insulting but I have done all of these things myself...
> 1. One of the baskets are positioned wrong.
> 2. The distribution block is on backwards.
> 3. Hoses are kinked somewhere.
> ...




No insult, I'm going crazy trying to figure it out and for all i know it could be something obvious. I don't think any of these are the problem though, there's a big stupid light bulb that fits into the trays, so they can really only go two ways. 



WaterLife said:


> Do you see air pockets in the green tubes?
> 
> I've had two SunSun canister filters that both had a little pin hole in the black plastic tubing that has the adjustable leveler (ribbed/grooved) for the surface skimmer attachment, so if the water level was below that hole (or if you have a hole/air/vacuum leak anywhere for that matter), leaving that hole exposed, air would be sucked in, constantly filling the canister head with air.
> 
> ...



I don't see any air pockets. I'll examine the plastic pieces, I topped up the water in case that was affecting something. I removed the whole surface skimmer piece earlier to see if that helped. Didn't disconnect the hoses from the fittings. 




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## Lonestarbandit (Feb 7, 2013)

jamielands said:


> No insult, I'm going crazy trying to figure it out and for all i know it could be something obvious. I don't think any of these are the problem though, there's a big stupid light bulb that fits into the trays, so they can really only go two ways.
> 
> 
> 
> ...



Fair point I forgot that was a UV model.
Still leaves the valve block on backwards (been there done that took hours of trying to figure out what was wrong with flow)
Or the hoses are pinched somewhere. Usually where they pass behind the stand etc.
That one took forever to find as well.
The only other possibility is the impeller has suffered some kind of damage and or is clogged up to the point it cant spin to its full RPM though that is unlikely?


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## Bandit1200 (Dec 11, 2010)

I just recently had the same issue with the same model. For me it was not a clogged impeller, but the housing around it. I'm talking about the channel between the impeller and where the hose disconnect is. I took it outside and blasted it with as much water pressure as I could get from the hose. I had checked everything as was mentioned before and could not figure out what it was until I looked at the impeller. After it was removed I could see slightly into the rest of the channel and it was almost completely clogged/packed with what I'm guessing was bacterial slime. You would be amazed at how much of that stuff came out.


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## jamielands (Jun 22, 2015)

Bandit1200 said:


> I just recently had the same issue with the same model. For me it was not a clogged impeller, but the housing around it. I'm talking about the channel between the impeller and where the hose disconnect is. I took it outside and blasted it with as much water pressure as I could get from the hose. I had checked everything as was mentioned before and could not figure out what it was until I looked at the impeller. After it was removed I could see slightly into the rest of the channel and it was almost completely clogged/packed with what I'm guessing was bacterial slime. You would be amazed at how much of that stuff came out.




Hmmmmm. I did rinse that under the tap, maybe i should examine it closer and try really blasting it 



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## jamielands (Jun 22, 2015)

Ok, I give up. I'm waving the white flag. I tried everything you guys suggested, and the flow improved slightly, but not enough. Since the fluval arrived i unboxed it and checked it out. It's a lot smaller of a canister than the sun sun, but surprisingly holds almost as much media. I was able to fit almost all the media I had in the sunsun into it, and the bit that I couldn't is made up for by the upright sponge that's in the fluval. So I figured I'd give it a shot.

Plus, my stand's cabinet isn't very tall so a canister doesn't fit inside. Since the tank is a centerpiece in my home and the filter is out in plain view I like that the fluval is slimmer, smaller and overall more visually appealing.

I set it up, I transferred as much media as possible from the old filter and got it running. The flow is MUCH better. The sunsun is almost silent, and the fluval makes a little more noise-but its brand new, so I won't judge until the new impeller has a chance to build up a little slime. I will keep the sunsun as a backup filter in case of emergency. Thanks everyone for your help! I appreciate all your suggestions, they were all good, unfortunately the damn thing just didn't cooperate. Can't hurt to have extra filters hanging around, eh? 


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## Lonestarbandit (Feb 7, 2013)

What? You can't stop now lol.
The rest of us want to know why!
This is like canceling a hit miniseries! Inquiring minds want to know!

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## jamielands (Jun 22, 2015)

Bahahaha there's no answer! I tried everything! I can still fiddle with it, the hoses are still on the tank, but I'm stumped. Maybe something got damaged when I broke it down a few days ago? I can't make sense of it. But I paid probably $60 for the sunsun, so maybe you get what you pay for? 

The tetras sure didn't seem to mind the low flow, they spawned all over the place yesterday, barf! 


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## OVT (Nov 29, 2011)

Had that filter, could not get rid of it fast enough.

Anyways, with the hoses attached, remove the "quick disconnect". Position over a bucket and open the ball valves using the lever on the top. If the water rushes out then it is not the hoses (unless there is air in the filter). If you get a trickle then the valves are not opening fully or have something stuck inside. You can look inside the disconnect to check if the white valve balls are fully opened or not (pull the hoses out of the tank first).

You already said that you are not seeing airbubbles in the intake hose and the filter is quet, so, I am leaving that area out.

My approach to troubleshooting is divide and conquer. Eliminate component pieces to narrow the problem down.

(I never had so many headaches with any other filter, before or after). Good riddance.


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## Lonestarbandit (Feb 7, 2013)

I've had the opposite experience and have 7 various Sunsun and never experienced such a thing.
That's why I'm so interested in what the cause is.
Good point about the valve block maybe that's what's gummed up?
I have no idea but it is perplexing.

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## Immortal1 (Feb 18, 2015)

The valve block comment raised an eyebrow - on my AquaTop 400 filter (bet it's the same valve block as Sun Sun) the cross bar that turns the ball valves broke. It is entirely possible the OP'S valve block is shut regardless of handle position.


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## Lonestarbandit (Feb 7, 2013)

Immortal1 said:


> The valve block comment raised an eyebrow - on my AquaTop 400 filter (bet it's the same valve block as Sun Sun) the cross bar that turns the ball valves broke. It is entirely possible the OP'S valve block is shut regardless of handle position.


Was wondering the same thing. Reminds me of your experience.


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## Lonestarbandit (Feb 7, 2013)

Valve block is 5 or 6 bucks on Fleabay. too easy lol.
I know as I had to buy one after 7 years one of mine let go.
Give ya 20 bucks plus shipping for it!
I am intrigued by it.>


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## jamielands (Jun 22, 2015)

I took off the valve block-no problems! Water rushed out, it still opens and closes fine with the handle. Strange 


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## Lonestarbandit (Feb 7, 2013)

WTH...... Now I want to know even more why this isn't working!!!!!
I want to tear it apart lol.
it MUST be then the passage in the head that another poster mentioned.
Very Very weird.


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## OVT (Nov 29, 2011)

My next step would be taking all the baskets and media out. If that does not improve flow, checking the head/impeller would be up next.


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## Lonestarbandit (Feb 7, 2013)

Sooooo........?
No news lol?


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## jamielands (Jun 22, 2015)

Shrug. No news. I switched to the fluval, I've examined the sun sun and haven't found anything interesting. Flow rate did improve slightly, but not back to 100%. I'm content to chalk it up to an old filter that I paid $60 for, got almost a year of use out of, and keep it as a backup (albeit a weaker one) in case of emergency. I'm guessing maybe the problem is in the head. Impeller is fine. 


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## gkai (Jul 16, 2018)

Hi, resurecting an old thread. I have exactly the same problem: my sunsun 404b had a really strong flow. But since I installed additional inline heater and valves I never got it back to original flow, and the bigger problem is that flow decrease slowly till it's almost nothing....until I purge air again.

It's not the added drag linked to the 2 addtional vlavles and inline heather, those are overdimensionned (I replaced the valves by PVC ones used in pool system, the aquarium/irrigation ones I tried before were utter crap), and the iline heater is a very clean, smooth tube surrounded by heating coil. When purged correctly, my sunsun start with a very strong flow, which decrease quickly after a few second, then stabilize to something nice (it was too strong before), but in 1 or 2 days decrease to almost nothing.

I suspect some air intake but it's not the whole story, my valves do not leak nor intake (I had a small intake that I solved), that's easy to check in transparent lines as you see the bubbles...

Maybe the filter itself is not fully tight...But it's strange, orings seems nice, I'ave added silicon grease, and it seems tight when off, no leaks not bubble sound when off or on...


Propeller is clean and not damaged, the various filter media are not clogged either.
Maybe there is something in the propeller exit channel (the volute of the centrifugal pump), but I do not think so...Especially as now that I have fixed valve air intake, my canister is crazily silent and smooth once started and purged.

Maybe it's the relative arrangement of inner baskets , filter body and filter head that has changed? I will check that. Annoying as the filter is cheap and quiet, and was extremely powerfull, but I need it to keep constant flow for more than a few days, else I will end up with no filtration during hollidays/business trips....


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## gkai (Jul 16, 2018)

Finally solved it, after a lot of useless cleaning and filter rearrangement...it was just the inlet sponge protecting my glass inlet pipe that prevented the flow. This part is under dimensionned and I have to be careful, but diagnosis was not easy: when siphoning the flow was quite normal, it's under strong suction that the sponge get slowly sucked in and progressively blocks everything...
For long term safety, I should create another inlet gard system...


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## MrT. (May 21, 2018)

"I should create another inlet gard system... " Or install a flow meter.


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## PlantedRich (Jul 21, 2010)

This seems to be something that I see on a number of different types of equipment and not just in the tank/fish world but big important equipment as well. We buy a piece and then we find it works so we modify it to work even better! 
But when things fail, do we look first at the mods we made or do we often find fault with the equipment we bought. My recommendation is that when we have something that works and then we change it and it doesn't work very well, don't blame the original equipment. Sometimes when we mod things, we need to be open to the fact that we might have screwed it up! 
My favorite personal screwup? I changed the media in an Eheim 2217 and then found the flow would quit after a day or so???? Drove me crazy until I found my "new, improved and cheaper" media was floating up against the section where the water flow goes to the impeller!


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## gkai (Jul 16, 2018)

Yep, a quite effective and general way to track down problem is to check at the last change, or all the changes since the time your device (or software) worked nice.
However, it is not as straightforward when your changes introduce slow failure, you do not know how long you need to go back in time to find the change that was not a good idea. I had this sponge gard since a month, and did other changes in the mean time (installed inline heater, changed the valves and part of the tubing,...
Same in your case: if your flow was reduced just after your media change, you would get it immediately. If it happen a few days after, it's already more difficult to catch.

Installing a flow meter may be a good idea, I want to progressively log my tank better, goind the arduino way. This open a lot of possibilities, but even if i find the flow decreased i will not be able to solve the issue remotely. When I am home, I can not measure the absolute flow rate but any significant change can be seen without monitoring equipment.

So I need to install a more robust gard. Going no-gard is nice visually (I started like that), but the suction in the pipe inlet is too strong: it sucks in shrimplets, kill adult RCS by tearing them appart, and can potentially kill any fish that would block most of the slits. It's that strong...With the sponge, I got a non-dangerous inlet flow and the flow resistance is not excessive...at first.

I looked into shrimp inlet gards, looks like a good solution and even ordered cheap ones. They are not well built, and my inlet diameter is too big for all the gards I find online, even the expensive one. I will probably try to modifiy my cheap ones to make them fit, or try to build my own: Only thing difficult is to find good stainless wiremesh, and then to glue or weld it in a visually pleasing way...


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## Rusticdr (Apr 5, 2016)

thedood said:


> If I might make a suggestion. Try rubbing vaseline or silicon grease around the head seal and reassemble. Make sure its primed and burped well. If that helps I would order a spare seal or two.


I am sorry for reopening this thread but since I have been experiencing the same issues in my sunsun 303a could someone pls explain what the head portion of the canister filter is? I have tried almost everything else. Cleaned the impeller, the channel between impeller and outlet and every other crap. Air is not getting trapped either.. it's a new one too. Maybe its product itself that's bad. Anyway hope someone enlightens me.. Thanks. 

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## Crazygar (Nov 16, 2006)

I'm experiencing similar problems with my SunSun 603B, I am opening it up this evening and seeing if my "mods" are the reason. I have a reducer on my output line to facilitate my Lily Pipe, but I am going to check the basket direction or media setup (I may have caused my own problem, with having the media bag on the bottom and sponges on top)...

Gary


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## Doogy262 (Aug 11, 2013)

I have three sunsun's working great for over two years but once when I cleaned the impeller assembly I did not seat it fully.It has a very small tab that needs to be fitted and tightened.After redoing that the problem was solved...


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## Crazygar (Nov 16, 2006)

Ha! I'm just across the river. 

This is a brand new filter, it was stock with poor flow. I did giggle it and managed to get some flow out of it, but not enough to be impressed. I will attempt readjusting my media this evening along with checking the impeller assembly. 

Gary


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## PlantedRich (Jul 21, 2010)

Some basics seem to be missing in the discussion and those little things can really hurt. One is when we add almost anything in line, we often reduce the flow. Look at the fitting you add inline and it is often added INSIDE the tubing. Take a 5/8 tube and add a 5/8 fitting and you DO not Have a 5/8 opening as the material of the fitting reduces the opening a lot. Add a media bag to hole the loose media and you have almost certainly added a flow restriction due to the bag material. 
When I get new equipment, I fight the urge to "improve" it with any mods until I have tried it and found what the design offers. Only then will I try any of my homemade solutions one at a times to see what I may have screwed UP!
I don't see it mentioned but one easy way to shut down flow that is hard to spot is letting apiece of the loose media get into the flow at some point. Whether it is Sunsun, Eheim or any brand, there are places where we can let a hard media item like one of the barrels slip into the tubing and since it moves around, we may not spot it. Turning the filter block the wrong way is an easy one to do! 
Just way too easy for us to fall into the trap of thinking the filter is bad when we are the main failure! 

For the question of what is the "HEAD"? The top portion of the filter which sets down on the canister is all called the head. Often has a large rubber type O-ring to seal it to the canister body.


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## Crazygar (Nov 16, 2006)

@PlantedRich, I understand that the reducer will definitely slow down performance on the output. I have extra hose here, I might readapt, install the stock spraybar for now and reorder a proper size lily pipe that will actually fit the hose. This i believe is one of the major factors in the reduced output.

Also, I moved around the canister filter so that the hoses were not crossing each and boom, much more flow, not a torrent but I can definitely see movement in the tank now. My output hose is longer than than it needs to be, I can trim some down and see if that helps as well.

"HEAD" is "HEAD PRESSURE" which is pressure required to push water upwards from point A to point B.

Gary


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## deeda (Jun 28, 2005)

Rusticdr said:


> I am sorry for reopening this thread... could someone pls explain what the head portion of the canister filter is?
> Sent from my SM-G950F using Tapatalk


I think this is the question PlantedRich was answering about what the head portion of the canister filter is.


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## KayakJimW (Aug 12, 2016)

Crazygar said:


> [MENTION=37989]..."HEAD" is "HEAD PRESSURE" which is pressure required to push water upwards from point A to point B.


Technically that is Static head which is Zero in a closed loop system. Only a problem with sump pumps or open designs 

Dynamic head would be friction/resistance from bent or crimped hoses, clogged media, ect. which was more likely the case with tangled hoses than length of hose. But if there's too much hose that's more opportunity for bends/ restrictions and should be shortened. 

In my experience reducing intake diameter reduces flow, but reducing output diameter increases the force coming out. Like partially covering a garden hose with your thumb to spray a long distance. Same GPH, just more force


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## Crazygar (Nov 16, 2006)

I definitely have too much length if it can form a nice curve, I think shortening things up will help further things along. 

Either way, I plan to reorganize the media as well, I have the media bag at the bottom and sponges at the top. Going to put the sponges at the bottom and media bag on top and no top piece necessary and see if that helps as well.

Gary


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## PlantedRich (Jul 21, 2010)

KayakJimW said:


> In my experience reducing intake diameter reduces flow, but reducing output diameter increases the force coming out. Like partially covering a garden hose with your thumb to spray a long distance. Same GPH, just more force


I fully agree with this idea but in the practical I agree only to a limited sense. We do see water flow in canisters as somewhat like a hose but when we get into actually putting a finger or any restriction on the filter tubing we will find it works a bit different due to the difference in pressure. A hose is likely to have 2-60 PSI and will push it's way through a restriction but if we put a finger over the end of a filter tube running about less than 10 PSI, it just stops flow! 
The result is that a gob of filter floss in a hose will just blow on through but in a filter tubing, flow stops? I might look at the filter bag as a suspect and try how it works without the bab before I would do much to rearrange tubing. My point being that the bag is more suspect and also easier to test than cutting tubing. :grin2:


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## Crazygar (Nov 16, 2006)

I didn't get to working on the hosing for the filter but did manage to shift a few things and it is producing more flow, but not enough. I also have considered that my thinking is based on extreme water current in a tank. I'll take a small video with my phone to demonstrate the flow.

I might just be me and the Lily Pipe. Going to gander at other peoples tanks as well to see what type of flow they have with these type of pipes in their tanks.

Gary


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