Amount of Filtration Required?

[Bone]

Hi,

I'm sure this has been discussed many times, but I couldn't find many posts about it in the few minutes that I searched.

I'm gathering the bits and pieces for setting up a new 90 gal cichlid tank (most likely tang's - not planted) and I was wondering about how much filtration I should have. I currently have a couple of 33 gal tanks with well over 10 times the tank volume turn over in filtering, which works well.

I have read that the rule of thumb is to aim for 4 times the tank volume turn over in filtration, but that you should "really" aim for 10X. Someone mentioned to me that the 10 X rule is more about total water "throughput", which can be achieved by including some power head(s), and not really about total filtration capacity, and that I should choose my filter(s) to allow for lower filtration volume (4X vs. 10X). Many filters provide info for what size tank they are "rated" for, but this usually lines up with only about 3 or 4 times the tank volume.

I will probably go with 2 filters on the 90. I like to have 2 filters just in case something goes wrong with one, the 2nd one will at least get me through for a little while during the repair/replacement time. I like the idea of having 2 canister filters, but I am curious about your opinions on whether I should opt for one canister and one HOB.

I have a line on a decent deal for a couple of used Eheim Professionel 2 2026's (172 GPH each) and an Eheim Ecco 2236 (158 GPH). I haven't decided on which one(s) I will get yet.

So, I would like some opinions on what I should be aiming for, as far as filtration volumes. If I should aim for something close to 10X, then the used units I am looking at would not suffice.

Cheers!

[lucius]

I don't have cichlids but I do run two filters on my 90 gallon planted with tetras.  I have a Fluval 406 canister and an AC110. The 406 is rated at 383 gph and AC110 is rated for 500 gph so I'm close to 10x.  The reason I chose to run at a higher filtration rate is so I can get away with doing bi-weekly water changes.

[Shawn84]

In a cichlids tank you never go wrong with over filter. 2 canister filter is the way to go. The bigger the better. I would also recommend run 1 HOB just to polish the water.

[Bone]

Hi,

Thanks for the info.

The two Pro 2 2026's might work then if I include a HOB filter too. I have an older Aquaclear 1200 (same as AC70 - 317 GPH) that I could move off of one of my other 33 gal tanks and replace it with something smaller.

That would give me 344 with the two Eheim 2026's and another 300 or so with the AC1200, for a total of about 650 GPH turn over, which is just over 7X the tank volume.

So, in general, would you experts say that I should try to get close to 10X filtration volume?

Cheers!

[Shawn84]

7x is good enough. The HOB I would just put filter floss in it and nothing as your using it as a polish. Main biological filtration is the 2 canister filter.

[sanny]

I would recommend a Fluval FX6.They are reliable canisters and many people recommend them as well. I believe they are rated for a 400 gallon.

[ajm1961]

For my 135 gallon cichlid tank I run two canister filters (Eheim 2217, Rena XP4) for mechanical and biological filtering plus two sponge filters for extra biological filtering.  Also, I run a Hydor powerhead for water current.
Been running this setup for about 4 years and it works for me.
I also agree that over-filtering is the way to go.

[exv152]

I will probably go with 2 filters on the 90. I like to have 2 filters just in case something goes wrong with one, the 2nd one will at least get me through for a little while during the repair/replacement time. I like the idea of having 2 canister filters, but I am curious about your opinions on whether I should opt for one canister and one HOB.

This is a wise approach. I have two canisters on a 75g, and a 125g, and it gives me piece of mind knowing one can carry the load if something happens to the other. Likewise, it works well for performing maintenance, alternating between canisters, ensures you always have a well seeded filter always running. 

[Mike L]

 This is an age old debate that I think has more then one answer but ultimately it's whatever makes you comfortable.

Here's something to ponder. A Rena xp2 is rated for up to 75g tank with flow rate 300gph = 4x turnover. Rena xp3  rated up to 175g tank with flow rate 350gph = 2x turnover. How does that work.

The following are quotes from one of the cichlid gods so to speak.Dr. Paul Loiselles book, Guide To African Cichlids 

1. "To function effectively, all the water in the tank must pass through the filter medium two to three times per hour.(referring to mech. filter.)"

2." A high flow rate is less important in a biological filter. For this type of filter to be effective, the waste stream must remain in contact with the bacterial flora long enough for the nitrifiers to work on the dissolved metabolites. It is enough if the water in the tank moves through the filter medium once an hour".

To me it is water movement that is more important so as to keep debris moving so they can be caught by the filter. Additionally it helps to stir the surface of the tank in order to maximize oxygenation.

I use on my 75 gallon tank, 1 2217 (259gph ) and 2 marineland 900 power heads (240gphx2) with attached sponges. roughly 7x turnover. If my filter was to breakdown the powerheads would still maintain water movement therefore keeping the bacteria in the substrate aerated. Your substrate is the biggest colony of beneficial bacteria and is in fact your best filter by far. Having to maintain 2 filters is a lot more work that I'm not sure is warranted but as I said at the top do what makes you comfortable.
Mike

[charlie]

If I`m not mistaken , filtration is one of the topics that is going to be covered by one of the speakers @ Aquamania next month.
Regards

[Bone]

Charlie - thanks for the info. I really should try to make it there. Should be lots of good info available.

Mike - thanks for the input. Good explanation. Do you have any HOB filters on your 75 gal to compliment your 2217?

Cheers!

[Mike L]

 Good point Errol. I was planning to attend that day for that reason.

Bone- Forgot about that. In fact I did have a Emperor 400 that crapped out about a year ago. Had it for 6 years  before it crapped out. Never added a new one because my parameters never changed so I didn't feel the need. The thing is you can always  add if the needs be.