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post #1 of 7 Old 01-09-2012, 09:10 PM Thread Starter
Stoke88's Avatar
Multiple filters per aquarium?

I see a lot of people who use multiple filters on their tanks. Tanks as small as 20-40 gallons. Why is this? Is there any advantages by doing this? I can see using multiple filters on large tanks but why the smaller ones?
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post #2 of 7 Old 01-09-2012, 09:53 PM
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If you're talking about goldfish tanks, that's pretty standard procedure. I run two HOB's on my 55 gal goldfish tank. I wouldn't do anything less. I know people who run two filters on smaller goldfish tanks because they got back info from LPS employees, but mostly these are temp setups until they can get something larger.

I've also heard of people running a smaller filter in the tank so that they have cycled media when they need to set up a quarantine tank.

But I'm also curious as to why people would overfilter if they don't have goldfish or other messy fish.


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post #3 of 7 Old 01-09-2012, 09:55 PM
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Well adding a filter has a few advantages but not really major enough to justify, I'll list a few;

Ability to over stock as far as the biological filtration is concerned - of course in order to keep nitrates down more frequent water changes are required since you are talking about the same volume of water.

With two filters you can replace the filter cartridge out in one and shouldn't have to worry about the dreaded mini cycle.

Being able to create more flow in the tank for species that might need it.

Being to cheap to buy a filter the right size for the tank, so using two smaller ones on hand to get the same effect.

More mechanical filtration (again probably due to improper size of original filter)

Keeping another filter seeded with beneficial bacteria to use in case you need to setup quarantine / baby tank - only reason you will see two filters on my tanks.

For most of the time its typically people misguided by the fact that if one is good then two must be better, which is true to a point but it can be harmful if you don't understand the processes at work, two power filters on a small tank > 40 gallons can actually create too much flow for certain species of fish. As far as I'm concerned, only thing need for filtration on tanks smaller then 50 gallons is a sponge filter and lots of healthy live plants to soak up the nutrients.
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post #4 of 7 Old 01-10-2012, 08:32 AM
It seems to me that there is a lot of confusion about filtration. Not the least of which is the silly notion that we need 4-10 times the aquarium size in gallons per hour (GPH) flow rate. More water flow through filter media does not make for better filtration. Better filtration only occurs when we filter water [often more slowly] through finer media. So, it's not about how much water we pump around, but how well we filter the water that we do. Think of it...if the water is well filtered, filtering every drop twice per hour would seem to be plenty...right? Skeptic? Okay, lets say 4 times per hour. So if we filter every drop every 15 minutes and don't clean the water...pumping it faster probably isn't gonna help

I had my filter setup with the standard sponge and bio-media and I was noticing tiny flects of detritus in the return water. Particles like you see when you use a gravel siphon. After I added some filter floss to polish the water in the final stage, the problem was solved.

Now one would think that multiple filters on a small tank just doesn't make sense. But then as I thought of this, I was pondering my 29h tank and two filters rated for 5-15g really any different than one filter rated for a 30g?

Although larger, another example is my 60g. When I bought the 60g I purchased the AquaClear 70 HOB. I really like the AquaClear design because in contrast to cartridge HOB filters, I/we can adjust the media type, order and volume. I was happy with the filter, but wanted a bit more media capacity. I guess I could have purchased a canister and shelved the AC70, but instead I ordered another AC70 filter. One filter has sponge, Seachem Purigen and filter floss (mechanical). The other AC70 is filled with Seachem Matrix and uses a Fluval Edge sponge pre-filter on the inlet tube (biological). Both filters are set for low flow / maximum re-filtration and use simple DIY water bottle baffles to further reduce return water flow.

I also hear a lot about folks adding more filters and/or powerheads because some mulm is collecting on the substrate. I also hear about folks with canister filters adding a HOB.
Especially if you have a planted tank, the mulm might better be allowed to decay and help naturally feed the plants (can you say organic aqua gardening?). Even in the unplanted tank, this material does not hurt anything and is easily removed with the weekly water change/gravel siphon.
Speaking of it, not to overstate the obvious, but the WWC is the very best 'filtration' as 'the solution to pollution is dilution'. Some 'stuff' just can't be filtered out.

So in some cases, multiple filters, regardless of tank size, may make good other cases, maybe not so much.

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post #5 of 7 Old 01-10-2012, 09:10 AM Thread Starter
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I can definitely see multiple filters on a GF tank because of the waste they produce. I was thinking more along the lines of what I plan on running. I have a standard 29g with an AquaTech 20-40 with no filters, only a Fluval Edge pre filter on the intake. The tank will be live planted with a pair of German Blue Rams and others I think of later. I just saw a people doing this and thought it had to be a good idea if everyone was doing it. But it looks like I'm goin to skip the other filter. I don't want to complicate anything in the tank.
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post #6 of 7 Old 01-10-2012, 10:46 AM
Originally Posted by Stoke88 View Post
I have a standard 29g with an AquaTech 20-40 with no filters, only a Fluval Edge pre filter on the intake.
I think it would be a mistake to run the AquaTech without a cartridge, sponge or bio-media inside to provide a platform for beneficial bacteria. The Fluval pre-filter is okay, but I think you should leverage the filter chamber.

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post #7 of 7 Old 01-10-2012, 06:23 PM Thread Starter
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I forgot to mention that it will have a filter pad in the filter. Its the older style Aqua Tech so its not the newer two stage filter or I'd just leave the white filter pad in there.
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