HELP: broken canister filter, high nitrites

Discussion in 'Filters and Filtration' started by Florian Pellet, Jul 1, 2016.

  1. Florian PelletWell Known MemberMember

    TL ; DR
    Canister filter has low flow rate. Probably the main reason why nitrites are peaking at .5ppm. Fish are unhappy. Pipes & propeller aren't clogged. What to do?

    Hey everyone,
    I'm panicking, I just realized that my canister filter has very low flow, way lower than what it used to be, and I have no idea why.

    I have a Eheim Classic 2213 with standard outlets and quality 12-16mm (1/2") tubing. Nothing seems to be clogged, i just checked all the tubing, the impeller, cleaned the filter media. I do have an inline heater but it doesn't seem to be the problem as water flows at the same rate with or without it.

    Water used to flow out at a decent rate, kinda surging out the surface a little. At the moment I have raised the outlet out of the water to create water agitation and oxygenate, and it's barely enough: the water just pours down lazily from the pipe.

    What can I do short term so that my critters don't die? I have rasboras (harlequin), betta and multiple species of shrimp (neocaridina davidi, neocaridina denticulata, caridina propinqua, caridina japonica, caridina cantonensis).

    For now I have an air stone in there, and my canister still running. I don't dare turning the lights off as I now low oxygen (planted tank) is an extra strain on the BB and I don't want my Nitrites to peak higher. I measured them at .5ppm this morning, and did a 30% water change since then. I thought the problem came from something else than my canister so I didn't look further into it (see

    Please please help!

    PS: just did another 10% WC.

    Here's a look at my outflow. This is for a 30 gallon tank.

    Last edited by a moderator: Jul 1, 2016
  2. Mom2some

    Mom2someWell Known MemberMember

    Bump. You already have an air stone. I don't have another great idea. Maybe those with more experience can help... CindiL, Coradee, jdhef?
  3. jdhef

    jdhefModeratorModerator Member

    Well if nothing is clogged, I would venture to guess that something is wrong with the motor. The best you can do until you get the filter fixed/replaced are some large daily water changes.

  4. OP

    Florian PelletWell Known MemberMember

    Ok thanks. From the video of my outflow above, can you tell whether it is indeed too slow? It's a 13mm hose (1/2"), about 1m above the canister itself (40").
  5. jdhef

    jdhefModeratorModerator Member

    I can't say for sure, but it does look like it may be too slow.

  6. CindiL

    CindiLFishlore LegendMember

    Hi, is this the tank you setup just a couple of weeks ago? You are fishless cycling? I know you asked questions on your filter but I'd like to address some other things first. Sometimes it is helpful to have an hob running at the same time as a cannister for mechanical filtration. You could pickup one of those and add it on whil you figure out whats going on with your other filter.

    What is the ph of your tank right now? What is the ph of your tap?

    Your ph of 6.5 is a bit low for nitrifying bacteria to grow at a very fast rate. It also makes me worry about your KH (carbonate hardness) and the ability to hold your ph steady. Do you know your KH?

    I would do a large water change (again) to get the nitrites back to 0. Have you been changing the water while cycling? If so, how often and how much?

    Do you have Seachem Prime in your area? Or Amquel Plus? I would pick up one of those to dose daily while cycling to detoxify ammonia and nitrites (up to 1.0) and keep your fish safe.

    You can also add small amounts of aquarium salt for prevent nitrite poisoning but we need to know your ammonia first.
  7. OP

    Florian PelletWell Known MemberMember

    This is the tank I setup a couple weeks ago, but I used the same canister filter I had on my previous tank, as well as all the substrate I had too (plus adding some more substrate). Basically, the canister filter was turned off for 5 minutes while switching from filtering a 16 gallon to filtering a 30 gallon. The new water in the 30 gallon had been conditioned with API AquaPur (chlorine, chloramine, heavy metals & stress coat). Theoretically it should have been more or less instantly cycled. And I had asked about that because I had nowhere else to put my fish in the meantime.

    After setting up this tank, I did 15% WC weekly.

    I have low pH and KH because I use technical substrate that buffers my water that way. So in my tank, i usually have pH at 6.5 and KH at 4.

    My tap is (tested with test strip)

    • 0 nitrites
    • 30 ppm nitrates (hard to read)
    • >21°d GH
    • 15°d KH
    • 7.8 pH

    Right this morning, my tank is (tested with test kit, except for GH tested with test strip)

    • .4ppm nitrites
    • 10 ppm nitrates
    • 0 ammonia
    • >14°d GH
    • 6°d KH
    • 7.5 pH

    Two amanos were dead this morning. I hope no one else died, hard to tell. For sure the betta, the rasboras, and the black king kongs are alive, the other are too numerous to be counted.

    Except for the last few days, I haven't been testing the water in this tank because I didn't think I was cycling. I'm still not sure I am, but if it is the nitrite peak of the cycling process, it couldn't have arrived at a worse time. I still think the problem is the low flow rate of the canister.

    I do live right across the street from my LFS. I'm going to go there and pick up some things. Maybe a culture of live bacteria and something for lowering nitrites.

    Still freaking out. Thanks for your help @CindiL.

    [EDIT 1] — telephone call from Eheim

    Following a discussion with Eheim, I made a video of the filter running without media. Looks the same...

    [EDIT 2] — second telephone call from Eheim

    Continuing with Eheim's advice, I tested the head of the canister without any obstruction.
    Last edited: Jul 2, 2016
  8. DoubleDutch

    DoubleDutchFishlore LegendMember

    The pump is okay. There seems to be an issue with the inlet. Could there be dirt build up in the connection to the cannister ? Does this type have a non-return valve inside? A small ball in a "housing".
  9. OP

    Florian PelletWell Known MemberMember

    No dirt, no valve... That's a real head scratcher. The Eheim guy just confirmed that the pump seems to be working.
  10. DoubleDutch

    DoubleDutchFishlore LegendMember

    Does look allright to me.
    Didn't have the guy had his meds hahaha.
    Try this again with the outlet connected (in a bucket).

    No blockage in the hoses? Do I understand correct that The flow isn't great without media as well
  11. OP

    Florian PelletWell Known MemberMember

    The result is the same with just the head plus a bit of hose until the tap (I use double taps to connect everything).
    I've also tried everything connected but the return hose, and then the flow is slower, but that feels normal...

    None that I could find.

    Exactly. The video above (the view of the outlet in the aquarium during daytime) shows the flow without the media. That's slow, right?
  12. DoubleDutch

    DoubleDutchFishlore LegendMember

    That's too slow indeed.

    Must be the inlet! Where did you place it?


    bought some ghost shrimp and there was a stow away. Just wondering if anyone knows what this is. Extra info it's a fresh water fish
    Last edited by a moderator: Jul 2, 2016
  13. OP

    Florian PelletWell Known MemberMember

    I took everything apart cleaned everything thoroughly. There wasn't much gunk (remember the install is about 2 weeks old) but flow seems to have improved. What do you think now? I can't remember if it's like it was before. Is this good for a Eheim 2213 on a 30 gallon tank?


    I also added a Arcadia Poly-Filter (multipotent remover) and dosed the tank with TSS.

    I think the situation might be under control (I'm just missing confirmation that the flow is enough). I'll test the water tonight to see how it has evolved.
    Last edited: Jul 2, 2016
  14. DoubleDutch

    DoubleDutchFishlore LegendMember

    What do you mean with "enough". Enough for what. In my opinion this is a decent flow and it is filtering a decent amount of water.
  15. OP

    Florian PelletWell Known MemberMember

    I guess I meant 2 things:

    • enough to filter my tank properly
    • enough to consider my problem fixed
  16. DoubleDutch

    DoubleDutchFishlore LegendMember

    Then it's enough hahha.
    Only thing is bacteria might have to repopulate (is this English) the filter.
    So keep checking your water.
  17. CindiL

    CindiLFishlore LegendMember

    In the short term until the cycle is complete you can use 1 teaspoon aquarium salt per 10g (mixed in some tank water) to prevent nitrite poisoning of your fish population and further deaths :)

    Just replace it when you do water changes until your nitrites are gone.

    See if you can buy Prime or Amquel Plus OR any conditioner that says it takes care of ammonia also. A bottled bacteria will be helpful but only if it's the right kind like Seachem Stability or Tetra Safe Start plus which both contain true nitrifyers. If you find Prime, let me know.

    That fish looks either like a minnow or tetra to me, I would say minnow though based on the color or lack thereof. Looks a bit like a rosy minnow.
  18. OP

    Florian PelletWell Known MemberMember

    Thanks all.

    • I did a Nitrite test, I'm at .3ppm (against .5 yesterday and .4 this morning after WCs).
    • I added a bit of salt as suggested (hopefully my plants will power though this).
    • I had added live bacteria earlier today, of a brand I trust (only found in France and Holland I believe).
    • One red cherry shrimp has died extremely suddenly, mid flight fell to the ground (but that was before adding salt).
  19. DoubleDutch

    DoubleDutchFishlore LegendMember

    Mwaaaa France and Holland ??? Don't trust those guys hahaha.
  20. CindiL

    CindiLFishlore LegendMember

    That tiny amount of salt should not hurt your plants or your shrimp :)

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