# GPH vs Bio and Mechanical



## Imaconvict (Feb 1, 2010)

So before I purchase a filter I want to make sure I understand what is best suited for the fish. There are many conflicting stories regarding GPH and it's benefits. The way I see it is if I have good Bio and mechanical filtration then cycling the tank twice an hour should be sufficient. Why would I want 5-9 times per hour? With 39 fish in a 120 gallon tank supported with UGJ I think twice an hour would keep things filtered and the bio load would be fine. Can someone please give me some direction on the differences.

Mike


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## smellsfishy1 (May 29, 2008)

Mechanical should be at a high rate, you want a lot of water passing through the filter media as much as possible to trap waste particles.
Biological should be slower, you want the water to pass the media slowly so it can detox the ammonia/nitrite, ideally.

It actually works out this way in our filters,the water passes through mechanical media before the bio media.
The flow obviously will slow down from the contact with floss, sponges or foam.
Also, to maximize bio-media efficiency you want the water to be prefiltered so it doesn't gunk up the bio-media.

To be honest with you, I have never had issues with biological filtration and fast flow rates in all of my years.
Plus, filters are not the only place that the bacteria reside so where they are found is different in every tank setup.

If you setup the filter correctly and do water changes according to the need of the bioload it isn't needed.
Over filtering is marketing hype in most cases or some hobbyists are assuming it prevents the need for water changes/cleaning....which it doesn't.


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## rgr4475 (Mar 19, 2008)

I agree with smellsfishy1. From experience I have under filtered and I currently over filter. One thing I can say is that the cleaning process of the filters is much easier with it over filtered. Where I had 1 canister that was taking the brunt of the load vs. 2 canisters sharing it, the 2 canisters seemed to dirty up less than the 1 alone. (Obviously) Now whether the price of adding another canister to make cleaning easier is worth it? Well that is a personal choice. But I still do the same weekly water changes regardless of what my filtration was.


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## aquariam (Feb 11, 2010)

Its not the flow rate in the tank its the flow rate through the media. 
Eheim classic canisters, for example, all flow water past the biomedia at about the same speed, and in a 'tornado/dna/helix' (you catch my drift) pattern. The higher the GPH the taller and fatter the filter so that the media still takes water at the same speed.

For a Malawi tank I'd run a pair of 2217's honestly at that size. They won't mind the current, not that it'll be much, and you can run four spraybars (2+2) along the back of the tank with one intake on either side and have full surface agitation and a perfect cylindrical tumbling action in the tank.


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## KaiserSousay (Nov 2, 2008)

You can not clean what does not get to the filter, GPH/Turnover.
The important thing is that the waste is processed.
You could have a healthier bacterial colony in your tank than in your filter media with a high flow filter, but less crud in your tank.
My thoughts are, So what. 
I don`t care where the toxins get processed, and neither do the bacteria.


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## Imaconvict (Feb 1, 2010)

Thanks for the replies but I still just don't quite get it, how much poop is generated in one hour by 39 fish plus as I mention I will be using UGJ to help push the poop toward the intake. If I where raising horses in my tank I guess I would understand it more. I guess there's just some of us that need to experience it to understand it.


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## smellsfishy1 (May 29, 2008)

How much poop they generate is going to be totally dependent on how much you feed them and how often.
In one hour.... probably not much.
In one day...... probably a noticable amount.

If your jets have strong current and keep the water moving, most of the poop should get picked up by the intakes of your filters.
If not, it settles which is why we vac the substrate.
The more GPH or water moved increases the chance it gets picked up.
This isn't really a biological issue more of a mechanical one.


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## KaiserSousay (Nov 2, 2008)

*I guess there's just some of us that need to experience it to understand it.*
:lol: 
Been a bit of a Ã¢â‚¬Å"Hard WayÃ¢â‚¬Â


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## Imaconvict (Feb 1, 2010)

'Just as often, bucking the previous experiences of the many has led us back to the Ã¢â‚¬Å"tried and trueÃ¢â‚¬Å".

I hope I'm not being misunderstood here, I am here asking these questions out of respect for the knowledge of the hobbyist on this forum so I can minimize the amount of "trial and error" I will most likely encounter. I maintain my 60 gallon with good results, clean, good parameters, happy healthy fish etc. and have had tanks in the past including Cichlids in the early to mid 80's but things continually evolve in the hobby and I read different opinions that can confuse the reader so I need to understand it for myself so I ask questions. I'm in the same boat with alot of you, I love the hobby but things can be expensive so I want to make good choices before throwing money at something. Some with respectable knowledge on this forum say GPH is just hype and others say you must have a high GPH, doesn't this warrant the question? I figure questions up front good or bad ones is money in the pocket for later and will keep me loving the hobby and not being frustrated by buying something that just didn't work out, so I figure the only dum question is the one you didn't ask. When I was a kid it was put water in, put fish in right away and clean it when it gets hard to see the fish, parameters, weekly water changes, GPH, Bio, whats that? Luckily for fish and hobbyist things have evolved and continue to do so, but I cannot evolve along with it without asking questions and sometimes being dense and or stubborn until I finally understand it, good for me, good for the fish and and keeps my sanity in check when the wife isn't hounding me for buying filter after filter til I get it right.

Sorry for the long post but I felt compelled to clarify,
Mike


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## fmueller (Jan 11, 2004)

In real life, one times turnover doesn't mean that all the water in your tank gets pushed through the filter every hour. It only means that statistically the volume of your tank gets pushed through the filter every hour. The difference is that even with one times turnover filtration, you could have a quiet corner with little flow, and the water in that corner only goes through your filter once per day. The higher your turnover, the more likely it is that the water from those quiet corners goes through the filters at least once in a while.

That said, GPH only measures how much water gets pushed through the filter. If GPH was the way to go to measure good filtration, your best filter would be a huge pump without any media!

As you have pointed out yourself, another important consideration is having good flow throughout the entire tank. Also important are filter volume, and limiting the amount of bypass around the filter media.

To give you an example, I am running a 125G with an Eheim 2260 filter of 500GPH leading to 4x turnover. I am also running a 75G with an Eheim 2217 (265GPH) leading to 3.5x turnover. With regard to GPH, this is on the low end of what most people here would suggest. Yet I find that I need to clean the 2217 only once every three months, due to a good current in the tank, little bypass around my media, and a large 6L filter volume. Due to the massive 18L filter volume of the 2260, I need to clean that filter only twice per year!

That all said, 2x turnover is very low for any cichlid tank. Even with a good UGJ system you should expect debris to stay in the tank for a long time before it can finally be picked up by 2x turnover filtration.


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## Imaconvict (Feb 1, 2010)

Thank you fmueller, 2 times was just a number I through out there for conversation purposes. The 2260 or 2262 were actually filters I have been looking at but with some recommendations for higher GPH I was also considering an fx5 due to it's 925 GPH. The tank I just got was originally going to come with an fx5 but the guy didn't want to part with it and gave me 2 Emperor 400 instead. I think I am going to be most comfortable going with one of the Eheim's and not worrying about a higher GPH.


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## fmueller (Jan 11, 2004)

Many people love the FX5, and it looks like a pretty nice filter to me. However, while it has almost 4 times the GPH of a 2217, and twice that of a 2260, it is just shy of the filter volume of a 2217 (5.9 and 6 liters), and a 2260 is three times as big (18 liters)!

Why does filter volume matter? I stuff my filters all the way with filter floss - actually, I use quilt batting from Walmart. Filter floss is cheap, and it does a great job at mechanical and biological filtration. You can let the filter fill up all the way with gunk, and that takes three times as long in a 18 liter filter than in a 6 liter filter. The less often you open the filter, the less you disturb your bacteria, the better is your biofiltration. Plus I'd rather spend my time watching fish than cleaning out filters :wink:

I believe an Emperor 400 has a media volume of about 6oz, which corresponds to about 0.2 liter. You can see why I might not be a huge fan of HOB filters :lol:

Frank


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## Toby_H (Apr 15, 2005)

It takes water movement to move physical waste into a filter intake. Your UGJs definitely supplement your fitlration with water movement to help accomplish this and should therefore be included in your "gph" or "turnover" when considering mechanical filtration...

Decor is something else that heavily impacts mechanical filtration. Heavy decor will break up water currents thus reducing the ammount of water movement your tank will have. Thus I tend to suppliment heavily decorated tanks with powerheads or UGJs to acheive mechanical filtration to my satisfaction.

Personally, I never worry about biofiltration once a tank is fully mature / cycled. The typcial aquarium will have a very wide variety of surfaces for the bacteria to colonize on and it will colonize in the areas that best serve it. So if I push water through the filter to fast for the bacteria's liking, it will colonize elsewhere... if I move the water through the fitler to slowly, it will spread itself out... a bacterial colony is (quite literally) a living breathing thing that will constantly alter itself to it's greatest advantage...

I feel "10 times turnover" is a great "rule of thumb" to give new hobbyists. But for those of us who are attempting to refine our filtration, we should not limit ourselves to such theories. Instead we should look at results. If your ammonia/nitrite are staying at zero... if you do not have stale/dead spots... and if the physical waste is collected to your satisifaction... then you have good filtration...


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## Imaconvict (Feb 1, 2010)

On my 60 gallon I'm using a Fluval 204 with 180GPH and have never had any issues. My parameters are and have been since start of 2010 Ammonia 0, Nitrite 0, Nitrates 10ppm, the only change has been my pH which went from 7.8 to 8.0. Being that I have had no issues I am figuring on doubling the GPH for my 120 gallon so I am looking at filters to accomplish this, right now I'm leaning towards an Eheim 2080 or possibly the 2180 because of the 500w built in heater.


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## KaiserSousay (Nov 2, 2008)

Can`t argue with success.
You seem to have found what works best for your tank.
That low a turnover rate would not work for me and mine.
Either clarity or parameters would suffer.
I only have one problem with multi-function equipment. If one part stops working, it drags the whole show down for repair.


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## Imaconvict (Feb 1, 2010)

I only have one problem with multi-function equipment. If one part stops working, it drags the whole show down for repair.

I share this concern with the 2180 and will certainly dwell on it until final decision time. I will have a back up filter of some sort for possible down time on the primary filter but I don't know if I want a back up heater as well. If I go with the 2080 then I will most likely run two heaters in the tank which would give me some heat if one should ever need replacement.


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## aaronjunited (Sep 29, 2009)

interesting subject lads. *Iamconvict* can you show me what your UGJ sytem is like?
Have you any pictures of it being made or anything like that. I'm in the process trying to work out where i want the jets to be as i'm putting rocks in my tank for mbuna.

Regarding the subject we are on, *** been given a fluval 305 filter along with a 4ft tank, *** never used cannisters, i have another set-up also being set up which you all know about its a 190l tank.

I'm planning on getting the 2073 eheim to go in that along with my fluval U3 internal filter which has 600 L/H flow rate. With the undergravel jets i'm wanting to put in, i think this will be more than a enough filtration for my 190l mbuna tank. I'm not experienced enough in this subject yet as this will be my first mbuna set-up and i'm hoping the above filtration will be enough to keep my water parameters and cleaniness of the water top notch.

What do you think?


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## fox (Jun 11, 2009)

I use a hydor 300W inline with a 2080 on one of our tanks. I actually use two 300W hydors but one is turned up a degree higher and rarely operates here in the NE.

I am not a fan of expensive heated filters for the obvious reasons.


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## Imaconvict (Feb 1, 2010)

aaron,

I haven't began the work on the UGJ's yet, I need to build a stand first after I finish the stand for my 60 Gallon which is trim and doors shy of completion, but from what I have gathered you want no more than three jets per pump and the placement is dependent on the way your rocks (decor) is situated. Figure out the rock placement and design the UGJ's accordingly, I will use threaded fittings so I can make necessary adjustments and have some freedom to move things around a little. I will post pictures one things get going.


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## aaronjunited (Sep 29, 2009)

ahh i see, ok i look forward to seeing your project then, i take it youl post in the DIY section.

Thanks for the above help, thats what i'l do, get the rocks sorted then the UGJ and i'l post my own in the DIY forum.

Thanks.


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