Question about upsizing

[Kate_rn]

Hello-

I have read through the plethora of knowledge on this site but still have a question.

I have a 55gal freshwater tank with bala sharks, angels, and a few other semi-aggressive fish. Tank has been running really strong for the last year, no fish deaths, stable water testings, etc. We are wanting to go up to 75 gal to give the balas and angels more room, not planning on adding any fish. Is there any downside to running to filters for a tank this big or should I just take the media from our old filter and add it to a new filter equipped for the larger size. We are running a canister filter right now and I don't remember the capacity it was rated for so unsure if it would be enough for the 20 extra gallons. We already are running two heaters in the 55 gal and wouldn't bother us aesthetically to run two canisters.

Thanks!

 

[FishGuest5123]

I actually like to run 2 filters in case one dies. My larger tank has 2. Good luck!

 

[Colin_T]

Hi and welcome to the forum

There are no drawbacks to running two canister filters on a big tank. In fact there are benefits with the main one being you still have a filter running if something happens to one of them.

Another option for you is to get a double tier stand and have the tank on top and put a trickle filter/ sump underneath it. The filter media, heaters, etc, live in the trickle filter, and the sump will give you extra water volume. Most big marine tanks run a trickle filter/ sump combination under the main display tank, and they are very good filters.

 

[AbbeysDad]

I'm gonna have to go against the grain here ...two canister filters on a 75g is overkill.* I know of 75g's running with a sponge filter or two. Save your money and buy plants. Now if your gonna keep the 55g along with the 75g. then you'll need another filter.

* Remember, good filtration is about how well we filter the water, not how much, or how fast we push water through media, or how many filters we have! Besides, filters merely trap particulates that continue to decay and pollute the water. The water is clearer, but not cleaner.

 

[Kate_rn]

Thanks all! I really wish we could run two tanks with a sump system, I really like the look of those! We dont have a good place for that set up unfortunately. Maybe some day, we'll have a better set up and I can get my dream of a salt water tank!

 

[FishGuest5123]

I'm gonna have to go against the grain here ...two canister filters on a 75g is overkill.* I know of 75g's running with a sponge filter or two. Save your money and buy plants. Now if your gonna keep the 55g along with the 75g. then you'll need another filter.

* Remember, good filtration is about how well we filter the water, not how much, or how fast we push water through media, or how many filters we have! Besides, filters merely trap particulates that continue to decay and pollute the water. The water is clearer, but not cleaner.

I may be misunderstanding you and please forgive me if I am but the amount of water going through per hour does make a big difference.

 

[AbbeysDad]

The accepted hobby 'rule' is that you need 4-10x GPH relative to tank size.
So for a 55g you'd need a filter flow of 220gph - 550gph.
I think you can slow that way down and still have crystal clear water. Or put more simply, if you were to filter every drop really well say two times an hour, it would be fine.
Not long ago on a fish related site on FB I saw a 55g tank with THREE Sunsun canister filters underneath!
Again, filters trap particulates making water appear clearer, but not cleaner. The 'dirty truth' about filters is that they are nitrate factories that trap detritus where it breaks down quickly and pollutes the water. And faster flow rates reduce the effectiveness of beneficial biology to convert ammonia and nitrites.
If you can have crystal clear water with a medium sized air driven sponge filter, what's a big canister filter with a high flow rate really doing for you?

In this case, as I mentioned, two canister filters on a 75g just makes no sense to me. Oh I know there are some in the hobby that have convinced themselves that "there's no such thing as too much filtration"....but there really is!

 

[Colin_T]

If the pH of the water is above 7.0, you want a filter or filters that can remove all the ammonia produced from feeding the fish, as quickly as possible. Two filters will remove ammonia faster than one filter. If the pH of the water is less than 7.0 then ammonia is less of an issue but nitrite can be an issue. Again two filters will remove any nitrite faster than one filter.

You don't need a huge filter or one that turns the tank volume over 100 times an hour, but on big tanks, two filters (one at each end of the tank) will be able to filter the water faster and more effectively, and remove any ammonia or nitrite from the water before it can do harm to the fish.

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Yes all filters can be nitrate factories so they should be cleaned at least once a month and every 2 weeks is great.

 

[AbbeysDad]

Gotta disagree Colin. For a second, lets set aside the fact that there is far more beneficial bacteria in the substrate than in any filter.
The beneficial bacteria colony(ies) size will be relative the the food (ammonia/nitrite) and oxygen in the system....and we can conclude that a single canister filter will contain plenty of bio-media to support the 75g tank. I suspect that there are countless 75-100g aquariums out there with a single canister filter. Another filter, or more bio-media is just pointless.
Lets not let this hobbyist waste a couple hundred dollars on adding another canister filter that s/he doesn't need.

 

[Colin_T]

For a second, lets set aside the fact that there is far more beneficial bacteria in the substrate than in any filter.

If they are using an undergravel filter, then that statement is true. But if they are using a reasonable sized power filter or some other filter, then most of the beneficial bacteria will be in the filter.

If there was sufficient bacteria in/ on the substrate, we wouldn't need filters to keep the ammonia and nitrite levels down because the bacteria in/ on the substrate would be sufficient to do the job.

If you remove an established biological filter from an aquarium, the ammonia levels in the tank water will quickly go up. That wouldn't happen if there was plenty of beneficial bacteria in/ on the substrate. Yes there is some beneficial bacteria in/ on the substrate, but there is lots of bad bacteria, viruses, protozoans, fungus and all sorts of other things in and on the substrate that compete for space with the beneficial filter bacteria, thus limiting their numbers.

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Is there any downside to running to filters for a tank this big or should I just take the media from our old filter and add it to a new filter equipped for the larger size.

Getting back to the OP's original question, you do not need two canister filters on a tank but there are also no draw backs to having two running on the new tank. Whether or not you want to buy a second filter is up to you, it probably isn't necessary and your current filter should be able to do the job.

If you want to use your current tank and the new tank, then you will need a second filter. The second filter can be set up using half the filter media from the established filter and half new media. This will give you two filters that are cycled and you can set up both tanks straight away.

Personally, I prefer two filter on big tanks just in case one fails. But filters are pretty reliable these days and don't normally fail.

 

[AbbeysDad]

If they are using an undergravel filter, then that statement is true. But if they are using a reasonable sized power filter or some other filter, then most of the beneficial bacteria will be in the filter......

We'll just have to agree to disagree.
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Beneficial bacteria (BB) attaches to nearly all hard surfaces in the aquarium. Bio-media is often rated by the amount of surface area it provides for the BB colony(ies). The substrate particle surface areas far surpasses the media capacity of any filter. Additionally, bio-medias in a filter quickly lose their effectiveness as they become coated with bio-slime and detritus. This happens very quickly if there isn't very fine mechanical media protecting the bio-media. Manufacturers know this and recommend replacing half the bio-media every other month or so. But hobbyists rarely do this thinking their bio-media is good forever. So the colony(ies) size increases elsewhere in the tank to compensate relative to the bio-load generating ammonia.
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But all of this has little to do with adding yet another canister filter to a tank. As I mentioned in a previous post, I'm convinced that the hobby rule of 4-10x gph flow relative to tank size is incorrect and 2x works just fine. There are many successful tanks with HOB's or sponge filters that don't turn over anywhere near 4-10x. I see the merit in two filters for a large tank, but only if their combined through-put is around 2-4x which is rarely the case. The hobby notion that "there's no such thing as over filtration" is just plain incorrect. Fast water flows reduce BB's ability to process ammonia/nitrites and serve more to stress fish than accomplish better quality water.
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With this I'll just step away from this thread. I hate to see hobbyists throw money where it does little or no good. Might better invest in fast growing floating plants (like anacharis or water sprite) that convert nutrients (aka pollution) into plant tissue, eventually removing by trimming.
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Kate - good luck and best wishes with your upgrade to 75g.