Do Fowlr Tanks Need Sumps?

Discussion in 'Saltwater Tank Equipment' started by CHAMELEON_BREEZE, Apr 19, 2019.

  1. CHAMELEON_BREEZEValued MemberMember

    I know that reef tanks bigger than 30 gallons need sumps. However, if I have a 100 or even a 75 gallon tank and make it a FOWLR tank, will I need a sump? Or can I use an Aquaclear 110 and a HOB skimmer on it?

    I've heard of people who had big FOWLR tanks that run on HOB and still have success, especially here in HI, where corals are not a common thing to see at the LFS (most of us have FOWLR tanks).

    Also, for biological filtration, maybe I can use all live rock and all live sand?

    Just wondering. I could still get a sump.
  2. stella1979ModeratorModerator Member

    Well, as you know, having enough rock in the tank will hold your cycle. Sumps are great because they increase overall water volume, but the main purpose of a sump is for nutrient reduction... which is why you often find them with a refugium and/or a skimmer.

    A large refugium will work better than a small one and HOB skimmers don't all have the best reputations, particularly those intended for large water volumes. So, on my 20g tank, a small HOB refugium does a good job, and on a friend's 25g, an HOB skimmer is also doing fine work. Would I want either of these on a 75-100g? Nope, but I am talking about reef tanks here. Reef tanks are more sensitive than FOWLRs, yet, even some fish and inverts are sensitive to 'dirty' water. So... perhaps you could get away with a sumpless large FOWLR, but you would need to stock it carefully and try to keep the overall bioload low. While a FOWLR can usually withstand higher nitrate and phosphate levels than a reef, NO3 and PO4 are algae's favorite food... and who wants a big ol' tank without as many big ol' fish as the tank can safely hold?

    This is just my opinion, and you're right that not everyone will agree and folks can make things work... but no, I absolutely would not have a sw tank over 50-60 gallons without a sump.
  3. JesterraceWell Known MemberMember

    Actually the cut off I usually recommend is a 4 foot long tank (ie standard 55 gallon). Anything below and HOB is fine. Anything above and I recommend a drilled tank with a sump setup. Even for FOWLR for a tank of that size I would still recommend a sump. Why? Bigger fish tend to produce more waste. If you have any ideas about any kind of Tang YOU NEED a sump. They poop so much that you need the sump system to help filter all that garbage out of there. My 4 inch Yellow Tang could fill an entire corner of my 90 gallon with poop 3-4 times a day and that was just 1 fish. There are also other factors like the protein skimmer which removes protein waste from the water for you. Although there are some nice HOB Protein Skimmers out there, they have nothing on an in-sump skimmer in terms of efficiency and effectiveness. They also promote coralline algae growth and increase flow in the tank. Add in the benefit of an easy refugium setup for Chaeto/Pods which provides natural filtration and excess nutrient removal, hiding of equipment and it's just an all around better way to go.

    You could try HOB, but it is really ill advised as you simply won't get the flow you want even if you run 2-3 110 HOB units and an HOB Skimmer combined and with the expense of all that equipment you might as well just buy a pre-drilled tank with a sump. Cutting corners on costs with larger tanks usually ends with a lot of frustration in the long run and lovely problems with Cyano, Dino, etc. because you aren't getting enough flow and nutrient export.