Over filtration? Should I add a 2nd filter ?

[newaquaentusiast]

Hey all

So I have a 243 litter rimless planted tank,
90X60X45

Been set for a few months and is completely cycled and balanced.

It has a 1,450 LPH canister filter - Fluval 407

But I have an additional Fluval 107 (550 litters per hour) without use,

should I add it to the tank or is that completely unnecessary?

Thanks!

 

[Magnum Man]

I personally like 2 filters in a tank, so they both are seasoned, and if you take one down for cleaning, you’re not reducing your beneficial bacteria too low…
Not sure if you can reduce your flow on those so as not to disrupt your tank too much…
By having the 2nd one running, your already set up with a cycled filter for your next tank ( after MTS kicks in )

 

[TwoTankAmin]

I have always been a believer in using multiple filters on tanks unless they are fairly small. However, the only time I have a canister on a well planted tank it has to be pretty big tank before I use more than the single filter. I do have a 2nd hang on filter on both my 75 gal. (287l) and I actually have 3 filters on the 150 gal. (568l). But the 3rd filter is 100% for mechanical filtration.

A well planted substrate is the best filter one can have. The plants use ammonium much faster than the bacteria use ammonia. Plus the plants actually host the bacteria, so we get a double benefit from having the plants. Moreover, some plants which have roots in the anoxic/anaerobic parts of the substrate will transport oxygen down into those roots where they release it. This results in the nitrifiers which require oxygen to develop. The end result is their is ntrate being created. And what then happens is above and blow the newly oxygenated area, zones of denitrification form.

This is an oilder paper from 1997 but it explains the above.

Petersen, N.R. and Jensen, K., 1997. Nitrification and denitrification in the rhizosphere of the aquatic macrophyte Lobelia dortmanna L. Limnology and Oceanography, 42(3), pp.529-537.

Abstract​

Nitrogen and O2 transformations were studied in sediments covered by Lobelia dortmanna L.; a combination of 15N isotope pairing and microsensor (O2, NO3−, and NH4+) techniques were used. Transformation rates and microprofiles were compared with data obtained in bare sediments. The two types of sediment were incubated in doublecompartment chambers connected to a continuous flow-through system.

The presence of L. dortmanna profoundly influenced both the nitrification-denitrification activity and porewater profiles of O2, NO3−, and NH4+ within the sediment. The rate of coupled nitrification-denitrification was greater than sixfold higher in L. dortmnanna-vegetated sediment than in bare sediment throughout the light–dark cycle. Illumination of the Lobelia sediment reduced denitrification activity by ∼30%. In contrast, this process was unaffected by light–dark shifts in the bare sediment. Oxygen microprofiles showed that O2 was released from the L. dortmanna roots to the surrounding sediment both during illumination and in darkness. This release of O2 expanded the oxic sediment volume and stimulated nitrification, shown by the high concentrations of NO3− (∼30 µM) that accumulated within the rhizosphere. Both 15N2 isotope and microsensor data showed that the root-associated nitrification site was surrounded by two sites of denitrification above and below, and this led to a more efficient coupling between nitrification and denitrification in the Lobelia sediment than in the bare sediment.

from https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.1997.42.3.0529

Mostly, what the filter on/in a well plated tank does is to do mechanical filtration and to provide circulation. In many tanks it also aggitates the surface which promotes gas exchange. In high tech CO2 added tanks the canister output is often oriented in a way not to aggitate the surface in order to keep the added CO2 in the water where the plants can get it.

 

[newaquaentusiast]

I have always been a believer in using multiple filters on tanks unless they are fairly small. However, the only time I have a canister on a well planted tank it has to be pretty big tank before I use more than the single filter. I do have a 2nd hang on filter on both my 75 gal. (287l) and I actually have 3 filters on the 150 gal. (568l). But the 3rd filter is 100% for mechanical filtration.

Thanks for your response,

If i were to put on the 2nd one,

How would you go about the positioning of the inlet outlet?
I currently have the 1 inlet and outlet on the same side, with the outlet pointing away and towards the side of the tank to create a circular stream from the back left to the back right and then it circles to the front and around

 

[GaryE]

You haven't mentioned what the fish are. To increase flow, you need fish that can swim in it it. No bettas.
If all is good, try to keep the flow from 2 filters moving the same way, to avoid creating turbulence. Natural water currents tend to move in one direction, and we should emulate that.

 

[MaloK]

I don't think you reach the point of over filtering with a total turnover under 10x.

You have around 6x and with the addition of the 107 you will reach about 8x.

If the fish are good at the moment, I don't think it will make a great difference when the plants will grow.

 

[newaquaentusiast]

Cheers guy's - appreciate your help.

So I tried selling the 107 without success so as I currently have nothing to do with it I opted to put it in. Maybe I will use it later for another smaller tank, (MTS is starting to take affect with me) so I might as well have it working and cycled...

The big 407 has the inlet + outlet completely covered by the plants.

Don't have enough room to hide the 107 as well,

so I bought glass lily pipe outlet and skimmer/inlet - and will set it up today.

The tank is quite big and has many parts where I reckon flow is low - so don't think the 107 (which isn't very powerful) will make a difference, will put it in the same direction, thanks.

It's a topical community fish,

a dozen colored widow's (green, yellow, pink, purple), half a dozen Bosmani rainbows, 4 molly's (2 black, 2 dalmatian), 2 sword tails (from the same family of the molly's, right) and two pleco's, so far. Will be adding more for sure. more of the same? or a another kind? not sure...
How many fish would you have in such a planted 243 litter tank with 8X over the filtration?


any of them don't like a good current?

Thanks again!

 

[TwoTankAmin]

Filters do not determine how much bacteria will be in any tank. What determines it the amount of ammonia being created. So the one thing we know adding another filter will not do iscreat any more bacteria. What it should do is cause the bacteria to spread out but not because there will be more.

About the onlt situation where adding a filter might help created more bacteria is in a bare bottom tanl with notheing in it but water and fish. The bacteria ned a place to colonize. But they are photo sensitive and need at least permanent shade if not darkness. No substrate and no decor means they have no place to live except in the media inside the filter.

If in such a tank there is not enough space for the amount of media in which the bacteria will live then adding a second filter would provide that space.

The reason for having multiple filters is that it spreads out the bacteria. If one of the filters fails, there is sill the other one and the bacteria there will start to repeoduce if there is excess ammonia available. However, when I do mulitple filters I use a pair that are smaller than what would be an acceptable single filter. Their total flow will be greater but this can minimze the current.

I like to have filters which have flow control. This lets one get a bigger filter than is needed for a gicen tank volume and size because it can hold more media. Then I turn down the flow rate to be where I wanted it to be for a smaller model. This is one of the reasons I use AquaClears for my hang-ons. They all have flow control.