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Are two better than one - cannister filters

18K views 10 replies 7 participants last post by  Byron 
#1 ·
Lets say I'm looking at a 50 gallon tank purchase, I'm thinking over the long haul I'd be better off with two smaller canister filters than one larger one. The one instance I'm thinking of is breaking down the filter to clean it. I can tear apart one canister filter and change everything out while the other filter is running, I'm thinking built up biological filtration here. There would be a bump in water conditions but certainly not as profound as changing out one large filter. Any thoughts on this?
 
#2 ·
It's not a bad idea at all. I have 2 HOB filters and every third wc I completely change a filter. Hasn't harmed me yet.
 
#3 · (Edited)
There should be no bump in water conditions do to a serviced filter, it doesn't matter if it is one big filter or two filters. It should not happen. If you mean completely replacing media, then IMO you are just looking for ways to waste your $ and harm your tank. There is no reason to replace media unless the sponges are falling apart. IMO replacing them unnecessarily will lead to a less stable tank. (I'm not taking about water quailty but that will also be effected.)

For a 50-55gal I would go for one canister filter. Any larger of a tank I would suggest a sump, or if you have $ to burn than 2 canisters. I personally would never run two canisters on one tank, simple do to the cost. A sump filter would be much cheaper and preform better biological filtration.

When looking for a filter you need to look at GPH. I prefer a turn over of 4-6 times per hour, everyone will suggest something different though. On my 55gal I run a Rena XP3.
 
#4 ·
I'd not go with 2 canisters neither. If you're worried about "maintenance" then either you had some real bad filter experience in the past or you're fiddling way to much with the filter which you should not do.
I had the Eheim 2213 on all my 50+g for years on end, never had a issue, no break downs, "maintenance" maybe ever 1 to 1.5 yrs that's it.
Also to consider if you hook up 2 higher end canisters like let's say Eheim to the 50g - You're over killing it if you're attempting to have it planted nicly.
 
#5 · (Edited)
Angel - why over filtration problems for plants?

Angel, why would "over filtration" produce a problem for plants. Something new I did not know - during my time in the hobby - was that bubbles from air pumps (usually through stones, but other means as well) drive out CO2. Why would "too much" filtration be a problem - interesting!
 
#9 ·
Angel, why would "over filtration" produce a problem for plants. Something new I did not know - during my time in the hobby - was that bubbles from air pumps (usually through stones, but other means as well) drive out CO2. Why would "too much" filtration be a problem - interesting!
Hey your tank, your headache do whatever you like. I'm only trying to share exp here.
Fact is over filtration will drive out CO2, it will prevent mulm built up which is proofed to enhance growth and health of the plant and more plants then non do not thrive well/ grow right with a current high flow in the tank ;-) Not to mention the fish matter on this...
 
#6 ·
Too much filtration will most likely draw out nutrients needed as well as cause more than enough surface agitation which will drive out CO2 as well. You also have to make sure that your fish can handle any sort of current said filter will produce. Some fish like a gentle flow and some a rapid current. You never want to go too little or too much. Yeah you always have some cushion to work with, but you want to set up what's ideal. And mikaila...I only change the filter pads when a vigorous rinsing doesnt work to remove debris, but actually, after running the two filters now, I haven't had too much of a debris build up in my filters at all...so ultimately, it's helped me. And I always reseed my filters with old filter pad material, as to not disrupt the cycle too heavily.
 
#7 ·
For that size tank, 1 cannister would be enough. If you rinse the bio media in used tank water, there shouldn't be any issues with losing bio matter.

I not aware of any issues with over filtration per see. For a planted tank you shouldn't use carbon in the filter. That would remove important trace elements. But filter floss and mechanical media shouldn't take away nutrients. I agree that flow can be a concern for both fish and for losing CO2. Depending on the filter, you can control this to some degree.
 
#8 ·
Oh yeah...I forgot you can control flow! Mine are always on max output to simulate river flow, however good filter will still filter the same number of gallons per hour, even with flow reduced.
 
#10 ·
I agree 2 filters are over kill, I ran a 55 with one 403 fluval, although I cleaned my filter more then once a year. maybe like 4 times a year.

The only thing I say is have a cheap power head and or good airpump and stone handy, the reason I say this is just in case. When I was cleaning the filter I broke the seal, I was able to stick the media baskets in the tank and have a powerhead force water through them. This allowed me enough time to order a new seal without the tank crashing.

I guess I could have just had random part laying around just in case but that seemed like a waste of $$$, you can always use a power head. While most filters never break why take the chance, for every tank I have I have a backup plan of some type to keep filtration going and save the bio media in the event of a break down.

One unrelated note when I went from a canister to a sump and and cleaned the filter floss each week or sometimes twice a week my nitrates went down. Always told my self I would start cleaning the filter floss each day, I think you all know how that turned out :) dang laziness
 
#11 ·
Assuming we are talking about a planted tank here, rsn48, then you will want minimal filtration and water movement. First, faster water flow through the tank is detrimental to plant growth (and many fish too) and there will always be a "battle" going on biologically, as I'll explain below. Second, you do not need biological filtration in a planted aquarium because that is exactly what the plants are doing, and not the bacteria.

The rate of water flow through the filter has an impact on the amount of oxygen drawn into the water, and carbon dioxide (CO2) expelled from the water in what we call the gaseous exchange. Surface disturbance speeds this up, as does higher flow filtration, airstones and bubble effects and powerheads. There are two detrimental issues to this: CO2 which is extremely important for plant growth is driven out of the water faster, and oxygen is brought into the water at levels beyond what is good for the plants. Plants have more difficulty assimilating nutrients when the oxygen level increases. But the more significant aspect is the CO2.

Submerged plants have difficulty obtaining enough CO2 in nature and in the aquarium; this fact is believed by many to be the reason for the inherently slow growth and low productivity of aquatic plants over terrestrial. Further, freshwater emerged plants have been shown to be more than four times more productive that submerged plants. The reason is because CO2 diffuses so slowly in water as opposed to air, and this limits the underwater plant's uptake of CO2 because the CO2 molecules don't contact the leaves quick enough to meet the plant's needs. Aquatic plants have to use enzymes to rapidly capture the CO2. When the CO2 levels in the water become depleted, these enzymes sit idle, so to speak, but the plant still has to provide energy to them. This results in a reduction in photosynthetic efficiency and therefore growth of the plant because energy is being wasted. Thus, any thing that removes CO2 in however small an amount will be detrimental to the plant's growth.

In a natural or low-tech system, the balance between the 17 nutrients (one of which is carbon) and light has to be there; so anything that may impact however slightly can become a critical factor in less success. The one thing we cannot "control" in this type of setup is the CO2, by which I mean that it is entirely dependent upon the fish and biological processes; with light we can control it, in intensity and duration, to balance, as we can with the other macro- and micro-nutrients through fertilization. Plants will photosynthesize up to the factor in least supply. Many have planted tanks that fail because the CO2 is the limiting factor, and algae will take over because it is better able to use carbonates for carbon than most (but not all) plants. The point here is that nothing should be allowed to negatively impact the CO2 in a natural planted aquarium.

The water flow is important for bringing nutrients to the leaves and roots, and keeping the leaves free of sediments. But there has to be a balance so as not to adversely affect the plants ability to assimilate nutrients including carbon from CO2.

Turning to the biological filtration point, in a well planted balanced aquarium the nitrification bacteria (nitrosomonas and nitrospira) are in very low numbers. The reason is, the plants use the ammonia/ammonium quickly, and little is left for bacteria. This is a domino effect; little ammonia and few nitrosomonas bacteria means little nitrite so few nitrospira bacteria, and finally low nitrates. Nitrates will frequently be below 10ppm in a planted tank; it is not because the plants are using the nitrates, although some do, but more it is because the plants prefer to use ammonium for their source of nitrogen and the nitrification cycle is minimal as a result.

The only purpose for a filter in a planted tank is to create an adequate water flow to benefit the plants in assimilating carbon and other nutrients, and to remove minute suspended particulate matter from the water column via the filter pads and media. This is mechanical filtration; chemical filtration is not recommended for planted tanks, and biological is basically unnecessary with respect to providing equipment.

Byron.
 
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