# What kind of flow rate canister is best for Walstad tank?



## batkidiii (Nov 12, 2014)

I need to purchase a filter for my 55 gallon, Walstad tank. I was wondering what kind of canister everyone here recommends. I am looking at Marineland C-360Canister Filter.


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## JG06 (Nov 5, 2006)

I'd think the Marineland would give you good service in an aquarium that size. I have an old Magnum 350 I'll be using for a 55 gallon aquarium after Christmas myself.


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## Guck (Nov 27, 2014)

This is the filters I use:
15 gal : Eheim 2211
25 gal : Eheim 2213
75 gal : Eheim 2215

Had a 2211 in the 2211 for a few months, but needed it for the 15 gal tank.


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## aquabillpers (Apr 13, 2006)

One of the good things about the Walstad approach is that filters are not needed for success. In fact, their use can cause CO2, always in short supply, to be forced from the tank. . Do you have a special situation that requires one? 

Bill


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## Guck (Nov 27, 2014)

aquabillpers said:


> One of the good things about the Walstad approach is that filters are not needed for success. In fact, their use can cause CO2, always in short supply, to be forced from the tank. . Do you have a special situation that requires one?
> 
> Bill


That's true. In fact, im her book, Diana Walstad is not big on canister. Her argument is that in case of power outage the filter can become anaerobic. When it comes back on all the nasty stuff goes in the tank. She favors power heads just powe4ful enough to ensure heat distribution. Makes sense to me.


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## Michael (Jul 20, 2010)

As the saying goes, there is more than one way to skin a cat. I have very good results with canisters.

Re CO2, loss occurs with excessive splashing, bubbling, and surface agitation. This is common with spray bars. If you arrange the outlet of the filter so that it produces a smooth circular flow in the tank with no surface agitation, CO2 loss will be minimal.

This fall, we had a 36 hour power outage--long enough to cause all the food in the refrigerator to go bad. I did nothing with my canister (or my other filters), and had no averse effects. But I set up my filters in a different way than the typical method, see below.

Keep in mind that Walstad recommends very low stocking rates for fish. I like to keep more fish in my tanks than she recommends, so the filters are insurance against accidental ammonia spikes and the like. The filters (including the canisters) are filled with biomedia and nothing else. There are sponge prefilters on the intakes of the filters which I clean when flow rate drops. I suspect that most of the time, the plants are removing almost all of the nitrogen compounds before they even get to the filter. So the filters primarily provide circulation. But if I accidentally over-feed, or a fish dies and I don't see it, the filters are there to help.

You definitely can have a successful tank with no filtration, but it does limit you in some ways. And for beginners and lazy aquarists like me, the extra margin of safety that biological filtration provides can be a real help.


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## batkidiii (Nov 12, 2014)

Michael,

What if my fish are looking like they need oxygen? Can I put in an air stone, or would that compromise the CO2?


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## Michael (Jul 20, 2010)

Fish gasping at the surface is an emergency, and an airstone and partial water change are the immediate response. Yes, an airstone will will reduce CO2 levels, down to equilibrium with the atmosphere, but no lower.

If fish are in distress, you must find the root cause and correct it. The most common causes are overcrowding and poor water quality.


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## batkidiii (Nov 12, 2014)

Ok. Thanks Michael. I am just in the process of setting up my tank, so I am trying to cover all the bases.


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