How Big Of A Filter Can I Go For A 25g ?

Discussion in 'Freshwater Beginners' started by KeeperOfASilentWorld, Apr 8, 2017.

  1. KeeperOfASilentWorldWell Known MemberMember

    Dear Experienced Fish Keepers,

    When buying the filter; I want to go for the Eheim Professional 4+ 250. If I up the size to 350 or even 600 and just adjust a slower flow, how will it work? What do you think about this idea?

    The reason I want to up the size is the higher number of trays and the higher bio-capacity.

    Thank you for your assistance.

    Happy Fish Keeping To All :)
  2. TexasDomerFishlore LegendMember

    I would go with the 250. The 600 would be way too much I think (even if you slow the flow), and even the 350 is more than 10x the GPH. You don't need that much.
  3. KeeperOfASilentWorldWell Known MemberMember

    Thank you for your immediate response. They have similar flow rates ( 250 = 950lph, 350 = 1050lph, not the 600, 600 has 1250lph ) but I really am obsessively thinking about the bio-capacity. Am I thinking this the wrong way, would the bio-capacities be similar since it is the same tank? Or would I really be much more comfortable in terms of water parameters? For example with a flow rate of 600lph and using a bigger filter?

    I am sorry to be this problematic, I really want it to be as good as possible :)
  4. TexasDomerFishlore LegendMember

    I think you're overthinking this. In a 25 gal tank, you won't have that high of a bioload. I think there's plenty of space for media in the 250.
  5. KeeperOfASilentWorldWell Known MemberMember

    The 250 model only has the mechanical filtration trays which also serve as bio media but the 350 has the bio specific media tray between the two mechanical ones. I know I am being annoyingly excessive but if I go for the 350 will it cause me a problem? The price difference I have between them is 10 euros.
  6. TexasDomerFishlore LegendMember

    Are you sure? I couldn't get the Eheim PDF to download for me, but in the pics off Amazon, I see two trays (and I think there's a third above them, hidden). I can't imagine a canister filter not having more than one tray.

    EDIT: Actually, just got it to download. Has more than one tray.


    If you want to go with the 350, go for it, but the 250 is overkill as it is, and personally, that 100 additional GPH and the one additional tray isn't that big of a deal for this size tank. I don't think there's any added benefit for this tank.
  7. KeeperOfASilentWorldWell Known MemberMember

    After careful consideration, just for the ease of my mind, I went with the 350 model with three trays ( Mechanical - Bio/Mechanical - Bio Specific ). It is only 27 gph faster than the 250 model, the product numbers stand for the maximum litres of tank it can handle.

    I know this was annoyingly excessive but the 9 euro price difference was very appealing to let go of the 350 ( it was on sale ) and I also wanted to have a filter I can use for a bigger tank in the future :)

    Thank you for all the help and sorry to put you through the trouble :)