350g tank with just sponge filters? Doable or absolute madness?

[HenryC]

I was wondering if it would be possible to filter a 10 foot long, 350g tank with just sponge filters. I don't think I've seen a tank above 100g filtered with just sponges, so I was wondering if it was doable. Thee tank will have about 4 oscars and 4 viejas.

Sponges seem to be the best bio filtration there is, according to an experiment I read somewhere in the past (will try to find it again to post it here). The person managed to remove a gigantic amount of ppm of ammonia in a day, with just a sponge filter. Much more than canister, I think it was a crazy number like 70ppm. 

The internet dictates that for such a big tank, I need a big sump to filter it. But I wonder, if I put, perhaps, 4-6 big sponges all supplied by a big air pump, and a couple powerheads to circulate the water, would that be enough to process the ammonia? The idea of a sponge only monster tank seems really cool to me.

Thoughts?

[Guppysnail]

I would think doable yes. If you had enough of them.   The frequency of need to clean them to remove the physical debris I would think would be more?..

[HH Morant]

I think there is a reason you don't see large tanks with just sponge filters.

 1st, there is aesthetics.  They take up space and they don't look good.

 I am not familiar with the experiment you mentioned, but it seems to me that the flow rate through a sponge filter is not going to be high enough to make it the equal of a canister or sump when it comes to biological filtration.  Beneficial bacteria needs flow.

 Of course, you can make sponge filters work even in a large tank by stocking the tank lightly.  If you want to avoid having your filtration outside the tank, sponge filters plus an undergravel filter might work and could let you have more fish.

 I think you are right that sponge or foam is the best biological filtration media - much better than the most expensive non-foam filter media.. See the aquariumscience.org articles on filtration.  I think it is better to have the sponge or foam in a canister or a sump,  where the flow rate is higher.

[Colu]

In large tank I don't think you will get enough flow from just using sponge filters alone 

[Guppysnail]

If it helps I stuff my canisters with coop coarse sponge. I only have a touch of bio rings and matrix. It works wonderfully.

Edited August 19, 2021 by Guppysnail

[Biotope Biologist]

With large volumes of water and high bioload the switch from sponge filter to sump is all to natural. The more volume and surface area you can get into the sump the better.

 

Let me know if you have any questions, they range from simple to advanced and you can easily raise live food cultures in more advanced sump setups. DIY sumps are fairly cheap, but if it's your first time doing one getting the plumbing and flow rate right can take a few attempts. Also make sure to build in fail safes so you don't end up with either a dry pump or an overflowing tank.

[Daniel]

You can go without any normal filtration if the tank is big enough. I haven't used any filter in my 8 foot 500 gallon for the last 14 years. You could call it "The tank is the sump".

Initially the tank had a lot of plants so I guess you say the plants were the filter, except

then 7 years ago I switched over to hardscape only, so maybe the plants weren't as important as I first thought. My current theory is there is enough surface area for all the good bacteria to live in an on, so maybe all that surface area and associated bacteria perform the biological filtration.

So what is added if the water pump pushes water through a sponge or a canister? In a smaller aquariums sponge filters or canister filters make a significant difference in biological filtration. But for the same reason I don't put sponge or canister filters in my outdoor pools I don't put filters in my big aquarium as they play very minor parts compared to what the rest of a large system does regards to biological filtration.

[OnlyGenusCaps]

I have no doubt that what @Daniel says is correct about surface area in large tanks.  Although, I will add the caveat that it looks like a pretty low stocking rate he's got going in there (please correct me if my assumptions from the photos are incorrect).  So, I'd be curious what you plan on putting in there because I suspect the bioload will make a bit of difference.  I think of this in terms not of numbers of the weight of the fish in the tank - this is why I have loads of Endler's in a 20 gal; put them all together on a scale and they weigh next to nothing!

I also think @Biotope Biologist is correct that most people end up using sumps in big tanks.  Now, I'm a self-proclaimed "sump-head", so I am completely biased, but sumps are great!  IMO, they are a far more flexible platform than canisters.  Done right, they are way less expensive.  They are easier to maintain on a regular basis, and over the long-term. 

On 8/19/2021 at 6:11 AM, HenryC said:

Sponges seem to be the best bio filtration there is

Additionally, if you want to get technical, I believe the most efficient bioreactor one can use in an aquarium is a moving bed bioreactor (MBBR).  Like sponges they are, typically, air driven, but they are also virtually self-cleaning (provided you have a means to mechanically filter out the sloughed off biofilm they discard).  I'm putting together a 250 right now with one in my sump for precisely these reasons. 

My suggestions would be, if you are going to have a medium to high bioload, then a sump of some kind will make water stability easier to accomplish (Daniel seems uncommonly talented in his fish keeping to me!).  Again, these are my opinions on the matter and how I am moving forward with a similarly-sized build currently.  

[ArchwayAquatics]

This tank sounds like fun! What else will be in the tank in regards to substrate, hardscape, any plants? As @Daniel demonstrates it can be done with less, and I share his outlook that for large systems the natural processes inside have greater capacity to keep a stable environment. In smaller systems the higher flow in the cannister/HOB/sump accelerate the processing of waste, and allow us to keep more than plants in small spaces. Somewhere along the line I heard someone say something to the effect of, 'anything is possible if you want to do the water changes' but I doubt that's what you have in mind 🙂

I briefly tried using two large coop sponge filters only in my 120g, but quickly found that without powerheads there wasn't enough movement in the tank, even with all the plants that were in there. I simply had too much stock in the tank for it to be effective without a lot of maintenance. 

I'm curious, if you're already planning to utilize sponge filters and power heads in the tank, why not mate the two, naked cannister style? 

If I were going to set up something like this (and I wish I could, I dig that 10' tank!), I'd stock one fish at a time over the course of many weeks to let the tank build up it's capacity to process. That way if there is a tipping point below the target load there's less risk of crashing the whole thing and mourning my fish. 

[Patrick_G]

My experience is with a 100 gallon goldfish patio pond with six growing fish. The filtration is a pretty minimal diy box but I don’t see any toxins. This will be the last season in this pond but my plan is for a 300 gallon with the same type of filter. 
If I were doing a large indoor tank I think I’d want the sump for it’s potential to automate water changes and top offs. 

[Biotope Biologist]

Oscars and vieja cichlids tend to have a high bioload, especially if you want to take advantage of their natural urge to hunt prey above the water line, which I plan on doing in a very distant future build. Think zoo/aquarium level build. 

 

While I think you could easily get away with sponge filters and good water movement along with a moving sand bed, the bioload on large cichlids forces me to want to recommend a sump. Granted there are plenty of cichlid keepers who use sponge, no substrate, and bi-weekly water changes to great effect.

 

I suppose it depends on what you want to accomplish with the tank. It's all just a balancing act, and I'm not very graceful so I like having sumps and well established tanks to take the hits for me.

[lefty o]

like daniel has proven, it can be done with little to no filtration.  a good balance of fish size to tank size , and not over feeding will be key. i myself like a little circulation, so in a tank that size i would probably put a sponge filter a foot in on each end, and one in the middle. i would not be adverse to trying sponge filters only in a large tank, but i would have a back up plan if they didnt get the job done.

[Aqua junky]

@Daniel love  the tanks buddy! I'd love to hear what all you've had in the tank present and in the past.  I'm really considering buying an 500 myself. I've got an uncle who owns a glass company so I could buy the glass at their cost. But am scared due to a failure cause that much water would flood my house lol. I flood my house my wife will kick me out to the Barn lol.

[Daniel]

On 8/19/2021 at 12:30 PM, OnlyGenusCaps said:

I have no doubt that what @Daniel says is correct about surface area in large tanks.  Although, I will add the caveat that it looks like a pretty low stocking rate he's got going in there (please correct me if my assumptions from the photos are incorrect). 

@OnlyGenusCaps points out something really important, which is keeping a fairly low stocking rate makes for a forgiving system. I can be a spectacularly lazy fish keeper. I need an aquarium that doesn't need me. Those weeks and months that I am passionate about fish are great for the fish, but what happens when I am distracted by some other interest and not much gets done in the fishroom? An aquarium that ran like a high performance sports car driving across a tight rope would work fine for me for a month or two until I got distracted and then it would crash and burn. Of course I would soon regret this, but I have done this enough times to know that at least for an aquarium in the livingroom, it needs to be able to run on autopilot. 🙂

For several years I had a school of angelfish in this tank. This was my wife's favorite setup ever. Drop some Tetra flakes in occasionally and....that's it.

The thing that always bothered me about the inch a gallon rule for stocking an aquarium was that the premise was something like "what is the maximum amount of fish I can put in an aquarium". If I had written the rule, it would have been backwards, something like "what is the minimum amount fish that will give you joy".

 

 

[Hobbit]

@Daniel do you have any wavemakers or anything to create flow in this tank? I had trouble getting enough oxygen in my 55g when I was trying to go full Walstad. (Asking here since sponge and other filters provide flow as well as filtration)

[Daniel]

On 8/19/2021 at 1:50 PM, Hobbit said:

@Daniel do you have any wavemakers or anything to create flow in this tank? I had trouble getting enough oxygen in my 55g when I was trying to go full Walstad. (Asking here since sponge and other filters provide flow as well as filtration)

Good point, filters provide flow which is a good thing. Here is what is under the tank. An inline heater (because I have discus) and a really nice Iwaki pump which is 7 years old, totally silent, and provides a lot of flow (think the max is 10 gallon per minute):

[Griznatch]

 I think the key for you is going to be the oscar (s). They have a huge bioload and they can be really destructive. The oscars I've kept would have destroyed a sponge filter. That was however in a 100 gallon, so when full grown he didn't have as much room as your 350 gallon would. Not sure if that matters to an oscar or not, I think it all boils down to how ornerey the individual is.
 

I personally think an enormous tank with a large fish, some big tough plants, and nice piece of driftwood would look incredible.

[anewbie]

A little depends on the rest of the tank; but scape and stocking. If you put in some of the larger pleco and cichlid they can be a bit messy and you might want more mech. filtration to remove uneaten food and waste. Sponge filters do a pretty good job of collecting waste as long as you take the time to clean them - at the end it is up to effort level and 'full picture' (stocking, fish requirements, ....). There are a lot of people who filter large tanks with nothing but a sump that has poret foam (which is basically the same idea of a sponge filter.... 

 

As others noted oscars can be messy fishes. Sumps generically sound expensive but if your sump is a 40B or 75 gallon tank loaded with poret foam sheets then it can be done for as little as $100 plus another $100 or so for the return pumps.

[Spicy Reef]

I have 4 bully discus, 5 fat candy cane tetra, 12 neon tetra, 1 guppie, 23ish red cherry shrimp, can't count the snails... only two sponge filters in a 30 gallon box. I just did my first water change in 6 months. Plan on doing one at least once a month as Cory has noted evaporation replacement is not a water change 🙂