How do you know when enough is enough? Filtration and water flow?

Discussion in 'Filters and Filtration' started by Colorado, Nov 29, 2012.

  1. Colorado

    ColoradoValued MemberMember

    So my new 56 gallon is about to "go live" tonight--filled, substrate in, Eheim 2217 running, heaters on, etc. I've read a bunch on filtration and there is so much variation in opinion about what is enough. Eheim seems to think the 2217 is good enough for a tank roughly three times my tank (up to 159g). Yet some forum members say it may just be enough--maybe not if I stock heavily, which I intend to do (not overstocked, but pretty full).

    Is the ultimate proof of adequate filtration what you numbers do? If ammonia, nitrate, and nitrite all stay where they should be then you're good or is there some more esoteric factors to consider.

    Also, what about simple flow. This will be a moderately planted tank and it is deep. How would I know if I need a powerhead or some such to move the water about more?


  2. Orion5

    Orion5Well Known MemberMember

    Hi! :)

    Your filter should turn your tank over 3-4 times/hour. That's probably why other people mentioned that your current filter may be just right on the limit of adequate filtration for the size of aquarium you have.

    If you're really going to stock the aquarium to its limits, might I suggest you either get a bigger canister filter (if they exist), or maybe an additional HOB filter to compliment it? Others here will undoubtedly have more precise information on this, but if I were you I would get another HOB filter just in case.

    This additional filter, depending where you place is in the tank, will also assist with more water flow if you need it.
  3. oscarsbud

    oscarsbudWell Known MemberMember

    I second the notion of having a second HOB filter for your tank. This way you have a backup on the off chance that something goes wrong with your canister. And it is a good place to keep extra bacteria media for a quick qt or hospital tank.
  4. Mmbrown

    MmbrownWell Known MemberMember

    I'm not certain if you have seen this, but I find this link really useful:

    Some times, you can't trust the manufacturer recommendations. (Remember when you first started fish keeping and the filter cartridge box said you had to replace them each month?)

    And, levels aren't always a tell tale way of deciding if your filter works well enough. For instance, my 20 long has great parameters, but I can tell there just isn't enough flow or uptake- some gunk doesn't get picked up and some plants are obviously not getting enough circulation. So, that plus reading the GPH link means I'm getting a new filter for Christmas :)

    I don't have much experience with bigger tanks but hopefully this post adds to other experiences and information you've received to help you make the right decision. Good luck!
  5. Jaysee

    JayseeFishlore LegendMember

    Do you mean a larger eheim? Because other filters come much larger - my big sunsun is twice the volume of a 2217. I think the 2260 is the next largest, followed by the 2262 - in the classic style. In any event, I agree, if the tank is going to be heavily stocked then additional filtration is a good idea.
  6. Orion5

    Orion5Well Known MemberMember

    @Jaysee: Any larger one would do, eheim or not.
  7. OP

    ColoradoValued MemberMember

    It still seems fuzzy to me about how one knows when you are underfiltered. I know folks look at turnover rate, but I imagine that dwell time probably has some importance. You could easily make a filter that turned over the tank 10 times an hour but didn't allow enough contact time between the water and the BB media. Is filtration GPH for aquarists like HP is for car people---more is better even if you hit a point of diminishing returns? I could buy a car with 500hp but I wouldn't make much use of all that extra power going back and forth to work---do I actually need a filter that has 5-6x turnover? I had thought about the FX5, but people said that was too large. The next step up for an Eheim is something like the G160, but reviews for it don't seem nearly as positive as for the Classic series--which was also $100 less. The 2260 is even more.

    Since the tank won't be fully stocked for weeks, if not months, I'll see how it goes. If I see some signs of underfiltration--the standard parameters seem like the only thing I can consistently measure other than, of course, fish mortality or morbidity--then I'll add an Aquaclear or Fluval HOB. I'd hoped to have a fairly clean look, but I don't want to buy another canister unless truly needed.

    Any other info/wisdom/opinions? Thanks.
  8. luke355027355027

    luke355027355027Well Known MemberMember

    Really you cant be overfiltered. I have two canisters in a 75 and 2 HOBS and a canister in my 160. I havent tested my water in a while but when i was trying to get my tank in tempo i would test the water every five days with liquid test strips. Finally after two months of testing i have figured out that ever 4 days my 75 needs a 20 gallon water change to keep nitrates under .20. Now i have just added a bunch of plants so that will affects my nitrates. Also remember stuffing your filters full of media can actually slow your gph.

    Secondly the ratings on a filter mean next to nothing. Most filters are rated for much larger tanks so that cant be trustworthy. Unless your fish are going in a whirlpool around the tank made by your output you should be fine.

    3. I have heard of people that take out their foam pads on their hobs and replace it with bio rings i actually want to take out my foam pads and add some seeded bio rings to see how it affects nitrates. Also sponge filters are good for housing beneficial bacteria just some thoughts.
  9. Junne

    JunneFishlore LegendMember

    I agree that 8-10 times turnover rate is the minimum for HOB's.

    I prefer to do more - my 5 gallon QT is using an aquaclear 30 at 150 gph, whereas my main 36 gallon uses 2 Aqueon filters and combined, is doing 600 gph.
    I use biomedia/rings in both tanks, as well as housing extra sponge media for future need.
    My Betta tank at 6.6 gallon has a 100gph turnover and has an adjustable flow with a pre-filter sponge.

    My water flow is not that strong, then again I use a prefilter sponge on my filters with my water usually up about 1 inch from the top.
  10. Orion5

    Orion5Well Known MemberMember

    It's interesting that you should mention dwell time, because that is very important in filtration as well. Personally, I use the rating pasted by the manufacturer because even if it isn't completely accurate it gives you an idea, and I generally try to decrease the flow to increase the dwell time of the water inside the filter. Apparently increasing the dwell time makes cycling an aquarium much more efficient. If I can find that article I'll post it.

    There are going to be many different ideas on this, so I completely agree with your decision to keep the canister and see how it goes- equipment can certainly be expensive as you said, and you already have a very good filter as it is. If anything though, as mentioned, an extra HOB filter does indeed come in handy if you need a fast quarantine tank. You might want to consider getting one regardless if your eheim does the trick or not.

    Good luck! :) I'm sure it will be fine.
    Last edited: Nov 29, 2012
  11. psalm18.2

    psalm18.2Fishlore LegendMember

    Another factor to add in how much filtration one needs is bio-load.
    If I have a 50g with only tetras then my bio-load is light, so basic filtration is fine. On the other hand, if I stock that 50g with lots of fish or big poopers, then I want as much filtration as possible.
  12. Jaysee

    JayseeFishlore LegendMember

    You had it right in the first post - the proof is in the numbers. If you don't have excess ammonia or nitrites, then the filtration is doing it's job. The concern about being underfiltered is in the threat of being maxed out - running at full capacity is not a good place to be.

    Turnover rate and contact time are inversely related. This is best shown in the difference between the approaches of HOBs and canisters. HOBs hold a limited amount of media, so they can only process so high of a concentration of ammonia in one pass. So, by turning the water over faster, a lower concentration of ammonia will be in the water so complete filtration can take place. Conversely, the reason canisters don't need as high of a turnover rate is because they hold a ton more media. With a lower turnover rate, the concentration of ammonia will be higher, but the contact time is higher so it can process it. Think of it like a QB throwing a pass - he can gun it to you or he can lob it to you - 2 different approaches that both put the football in your hands.

    The law of diminishing returns applies here too. You get to a point where the added filtration doesn't accomplish anything. IMO, more than 10x an hour. But, for many applications its lower than that. Plants also consume ammonia and nitrites, so you have to consider them as part of your filtration system. It's the tanks that don't have live plants that really need the bigger filtration systems.

    I would add something to improve circulation in the tank, whether it's a powerhead or another small canister. The small eheims are cheap, and that's all you'd need.
  13. Orion5

    Orion5Well Known MemberMember

    Jaysee, can I blog your post so that I can save it? :) A wealth of information.
  14. OP

    ColoradoValued MemberMember

    Thanks all. An interesting conversation. The Eheim is up and running and we'll see how she goes once there's an actual bio-load. My goal is a community tank of smallish fish with a fair number of plants so the Eheim may well keep up with it fine. I'll look into a powerhead or maybe an HOB like a Fluval C2 or C3. Those, I imagine, would increase both my circulation some and add a bit of extra filtration---with the safety margin of some backup and a filter ready for a QT. Thanks again.
  15. Jaysee

    JayseeFishlore LegendMember

    haha you can do anything you like - it's public domain now :)