Can I run a fish only marine tank on external filters?

[48Valves]

Afternoon all,

I've now had enough of my Mbuna killing each other. I've tried all sorts to get them to calm down but they just won't.

So they are going and I'm pondering what to replace them with. My tank is 4ftL by 2ftH by 1.5ftW and running 3 external filters.

My first thoughts was an amazon type scape with a large school of neon ore cardinal tetra.

But then I thought why not marine? I cant go with a sump as my cabinet has a divide in the middle and I don't want to shell out on a new tanks and equipment.

So as per the title. can I run a fish and live rock only marine tank on external filters?

If so is there anything else I would need? what would be the best media? are there any fish that would be particularly suitable to this kind of setup?

Thanks in advance.

[lufbramatt]

I'm no expert but from my chats with the lovely lady that runs the aquatics shop in Dartford, you can do this. The filter media is the live rock in the tank and you can fill the filter chambers up with smaller chunks of live rock but they are mainly there to provide circulation. Then you can get an in-tank or hang on back style protein skimmer to take out the nasties.

[Turn7]

Not get many marines' in a tank that size, puls youlll have to change/upgrade all your lighting.

It could work if you sensibly stocked it, and got all the right filter media.

Plenty of specialist Marine forums out there.

[Jasandjules]

Yes you can. But it can be more difficult as the filters increase nitrates.

What would you be looking to keep? A sumped tank is far easier.

[Roastie ITR]

I've currently got a small marine tank, but I'm thinking of converting my larger freshwater tank to marine that has an external filter.

Plenty of people run their tanks using external filters, so it should be entirely possible.

It's best to avoid the bioballs & the filter matting as these can be a nitrate trap as mentioned. If I go ahead I will prob just run floss & Siporax inside the filter.

As for what else you need, a skimmer would be highly recommended.
What kind of lighting do you have? If they are T5 bulbs, hopefully you can just get away with getting some marine white & marine blue bulbs.
Wavemakers would also be recommended.
Then it would just be a case of adding the substrate, live rock & salted water.

[48Valves]

Thanks all

I already have a marine LED so lighting isn't a problem. I can always build a new one if need be.

To be honest I think I'm going to stick with my original plan and go with the tetra.

I'm going to start saving for a proper marine set up.

[SeeFive]

I ran a marine set up in a 4 foot Sea Bray years ago on two high flow large canisters to filter the tank volume, and a slow canister via UV to kill Protozoa.

10% water changes twice a week kept nitrates in check, fish (and bloody rock anenomies) flourished, but I steered clear of the more delicate angels etc.

It can be done, and in my case was not too much of a time consuming thing. It pretty much ran itself with the exception of water changes.

[S11Steve]

There is a very large aquatics shop in Stockport that swear by external filters on all of their marine tanks.

The general consensus is that it can and does work, but needs a bit more monitoring and testing to keeping nitrates under control. The other issue is oxygenation of the water that would occur in a sumped skimmer is not there, so you'd need a lot of surface movement in the tank to make up for that.

It's a slippery slope though... from my 120l tank that I got dirt cheap of ebay as a full set up, I'm now on a 1200l mixed-reef, feature wall tank. In 18 months...