# Over Filtration / Bacteria Concentration / Water Changes?



## lonestar (May 16, 2008)

First, their is the question of overfiltration, is it possible? I've read that once you have enough biological filtration to combat bio-load, then extra is just extra. I'm thinking more bio-load needs/feeds more bacteria = bigger filter; less bio-load needs/feeds less bacteria thus you need less filtration?

I guess one way of looking at is that if you have a HOB/HOT filter with one foam pad and water quality is good you really don't need to add more foam. Adding more foam without increasing bio-load would cause same amount of bacteria to spread over more area since the food supply in the bio-load has not changed, ie.. less bacteria concentration....

Now on the other hand, leaving only one foam pad in HOB/HOT increases the bacteria concentration of that single pad, and it still adequatly handles the bio-load.

BUT, what about bio-load fluctations in the same tank ie. accidental over feed, skipped water change, ovestocked? If the single pad bacteria concentration is maxed, then it can not keep up with any additional bio-load due to fluctuatin. Although additional media may reduce the bacteria concentration, wouldn't it allow for additional growth to combat these bio-load fluctuations.

Applying above theroy, would over filtration allow for fewer water changes? And would enough filtration ever become self supporting like nature, ie. no water changes? Sure would be nice, especially on large tanks, toting around 15-20G water isn't easy.


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## lonestar (May 16, 2008)

Oops, accidentally posted in DIY, could someone move to Tank Setups or


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## Rick_Lindsey (Aug 26, 2002)

Most people do water changes at a schedule dictated by their nitrate levels, to keep it at a level they find acceptable.

Regardless of what kind or how much filtration you have, your fish are going to poop a certain amount based on how much you feed them, organic matter is going to decay based on how much you put in the tank (uneaten food, dead fishes, etc.).

X amount of organic matter (whether eaten and then pooped, or simply decayed) will generate Y amount of nitrate once the nitrogen cycles completes (ammonia -> nitrite -> nitrate), regardless of whether or not you're overfiltering.

Overfiltering can help you recover from ammonia and nitrite spikes more quickly, but it isn't going to affect the required water change frequency.

-Rick (the armchair aquarist, who has been wrong before, will be wrong again, but doesn't think he's wrong in this case)


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## MalawiLover (Sep 12, 2006)

Filtration level and bio-load capacity are different things, though inter-related.

Filtration level is mostly how much water volume do you turn over. More turn over (number of times the complete volume of your tank makes it through the filter in a set period of time) will allow you to have a higher bio-load capacity, but no matter how fast the turn over is if you only have two little fish in the tank, your load capacity is still two little fish becasue there is only enough waste to feed a small bacterial colony.

The higher the filtration rate, the large a capacity you can achieve in the end, but you will still have to build the colony up slowly so the bacteria can compensate for each added waste producer.

Does that make sense?


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## lonestar (May 16, 2008)

I sorta understand the turn over,

say 100 gallon tank 
5X/hr = 500 GPH
10X/hr = 1000 GPH, or 2 x 500GPH......
More turn over allows the water to be filtered more often, thus efficiently reducing ammonia & nitrate.

But how to compare water being filtered by 2" of foam media, vs, 4" foam media? I'm sure at some point there is a trade off in GPH vs, amount of media filtration, but generally speaking more flow would require more media for adequate treatment.

For example, which would be better, for simplicity I will stick to foam, as different filtration methods/media adds a whole new dimension.

1. 500 GPH w/ 4" foam media
2. 500 GPH w/ 8" foam media
3. 1000 GPH w/ 4" foam media
4. 2000 GPH w/ 2" foam media

Obviosly 2 is better than 1. How about 2 vs. 3 or 4? Would increasing turnover, but with less media reducing biological interaction, give same results. I have notice most suggest 10x turnover for HOB/HOT, but only 5X turnover on overflow/sumps.

So this leads me to beleive bigger is better and at some point, given enough meda, we could achieve 100% biological filtration elimiating need for 'regular' water changes, although it may be impratical for hobbyist say 100G sump for 50G Tank

Isn't nitrate harmless, its the decomposition of amminia-nitrite-nitrate that where concerned about. Poop requires filtration....More poop requires more filtration to efficiently break down ammonia to nitrate.

Makes sense to me, but I'm not a chemist..


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## MalawiLover (Sep 12, 2006)

Nitrate isn't harmless, its just less tocix. There are longer term issues with nitrates. It shortens lives and impairs the immune system. It also can slow the growth rate of fry. Thats why no matter what type of filter you have you still have to do water changes to remove the nitrates (unless you have a very heavily planted tank and a low stocking level, but thats another story). However, the lower the bio load, then longer you can go between water changes. The goal is to try to keep the nitartes low by not overstocking and doing water changes when the tank needs it. For most of us that usually means about once a week. It is generally recomended that you try to keep the level below 40ppm (20ppm is better). Depending on your stock level, that could mean you need to do a water change more or less often than the average.


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## toffee (Feb 11, 2006)

A lot of planted tanks have very low nitrate, although the keepers of those tanks still do weekly wc. For us cichlid keepers, it would be harder to keep a densely planted tank. Trust me, I tried, but 10" cichlids almost always win the battle over 20" plants.

But you can do a aquaponic, ie grown plants outside of the tank by pumping tank water though them so the plants have a chance to absorb some of the nutrients in the water.


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## Rick_Lindsey (Aug 26, 2002)

lonestar said:


> For example, which would be better, for simplicity I will stick to foam, as different filtration methods/media adds a whole new dimension.
> 
> 1. 500 GPH w/ 4" foam media
> 2. 500 GPH w/ 8" foam media
> ...


Define better? How big a tank is this going on? What sort of filtration are we trying to achieve? Do we have UGJ's to keep the "gunk" suspended till it gets into the filter intake?

That said, for a given system, choice 4 is going to require the most frequent maintenance . Choice 2 may or may not provide enough flow to get the gunk into your filter before settling into your rocks,shells,gravel, or other nooks and crannies.

Most people want to get the gunk into their filter, which keeps it out of the tank, but means your filtration media is going to get dirty faster. Of course, if you clean it out frequently then you can get rid of gunk that might otherwise be deteriorating underneath your driftwood.

It's hard to say which is better without more specifics on the tank, and really the placement of your water returns, intakes, and so forth is going to impact how "good" your filtration is more than your base GPH.

No amount of "overfiltration" is going to eliminate the need for regular tank maintenance, though, unless you're talking about automatic water changers and the like -- that's a whole new ballpark, and I would consider that "automating" the maintenance rather than removing the need . You put food into the tank, it turns into nitrate. A fish dies, it turns into nitrate. That nitrate has got to go, and using a bigger filter won't affect how much of it is in your system.

If you want to start talking algal scrubbers, plant filters, denitrators, etc. then the answer may vary, but i assume you're talking about basic biological and mechanical filtration.

-Rick (the armchair aquarist)


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## lonestar (May 16, 2008)

Makes sense....



Rick_Lindsey said:


> Most people do water changes at a schedule dictated by their nitrate levels, to keep it at a level they find acceptable.


I guess rule of thumb is to monitor water to help determine maintenance schedule.

How can we justify or rule out need for additional media?

Comparison for 55G:
AC110 (500) w/ one foam cartridge vs. AC70(300) w/ 2 or even 3 foam cartridges.

Which would you choose? Although most would recommend higher GPH (500) and market the fact that you have much more room for media, but why over filtrate if it is not necessary or beneficial?

EDIT
It is a question of GPH vs. availalbe biological filtration interaction?

Another good example you migh relate to with gas $4/gal is MPG. 
Something small and quick that can zip around and make several trips, or a large slow gas guzzler that can carry everyone/everything in one trip.


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## Rick_Lindsey (Aug 26, 2002)

For a 55 gallon, with a HOB style filter, for a typical "crowded" malawi tank, I'd choose the AC110. My AC70 could only fit 2.5 foam cartridges, but that's probably still only the same amount of foam as a singel AC110 sponge. FWIW I don't think the AC110 really pushes that much more water than the AC70 (I don't remember the specs off the top of my head, but in the old parlance, the 500 wasn't even spec'd at 500gph anyways).

Manufacturer's recommendations are typically provided based on a "typical" tropical tank, not a crowded cichlid tank. I suspect that most people go overkill on their overfiltration, and would be just fine with considerably less filtration. Most of them also use multiple filters though, which imho adds something much more important than overfiltration : redundancy. I would take 2 AC70's over a single AC110 on a 55 gallon tank, and alternate my maintenance so I've always got one "established" filter that doesn't get monkeyed with. Things can go wrong when you clean a filter... oops, I accidently dropped my biomax media into the chlorinated tap water. So much for my cycle! If one filter sucks some algae and the impeller gets clogged, and you don't notice for a week, your fish will hate you a little less if you had 2 filters than if you only had the one.

Particularly with the AC filters running multiple sponges or sponges with floss, then we start talking about mechanical filtration, where GPH matters more imho than in biological filtration, and where "more" is still "more", until your water is crystal clear (and few people have truly crystal clear water). That has more to do with aethstetics than fish health though.

-Rick (the armchair aquarist)


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## lonestar (May 16, 2008)

Rick_Lindsey said:


> My AC70 could only fit 2.5 foam cartridges, but that's probably still only the same amount of foam as a singel AC110 sponge.


I knew someone would pick up on that.....

For discussion purposes I would have said 2X or 3X foam..
500 GPH w/ X cubic in foam
300 GPH w/ 2X cubic in foam or 3X cubic in foam

Make sense what you said about mechanical filtration though, more flow would definately suck debris over to filter better.

Unless your talking about
500 GPH w/ X cubic in foam
2x 250 GPH w/ X/2 cubic in foam

some may prefer 2 smaller HOB's to minimize distubance to biolical filter by alternating cleanings at each water change, but now you are 'sucking' from 2 locations.

Again, it all comes back to tryin different things and monitoring water to see what works best. I guess I was hoping to maybe hear from some first hand experience...


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## MalawiLover (Sep 12, 2006)

By having a larger area for bacterial colonization, you can have more bacteria with less affect on the flow. If you cram 2 billion bacteria on a 1 inch sponge, you will have less flow through than if you put the same numberr of colonies on a 6 inch sponge. Some of the colonies in the center may not get optimum flow (ie supply of food) and may die or be less efficient, there by lowering your filtration capabilities.


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## kornphlake (Feb 12, 2004)

Lots of speculation here but nothing real tangable. I haven't done a fishless cycle because I've been able to get media from established filters for all my tanks, for those who have done a fishless cycle on more than one tank with different size or gph rated filters, can you tell a discernable difference in the amount of time needed to convert 4ppm ammonia to 0ppm ammonia based on the filter flow or media capacity? As far as I know it's never been tested in a scientific way. If I can come up with a spare filter this month I'm going to do some testing on a rubbermade bin and different filters and media I have.


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