How much bio-filtration do you really need?

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Moloch

Feeder Fish
MFK Member
Sep 8, 2010
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Raleigh, NC
I decided to clean my filters today which got me thinking about some issues I've been having with my setup. Currently I'm running a 90g FW planted tank thats pretty heavily stocked with two Rena XP3's and one XP1.

The xp1 is purely mechanical. I've 'modified' it into a powered gravel vac in addition to being a regular filter, it gets thoroughly cleaned at least once a week.

The xp3's are mostly biological. In one I have fluval pre-filter media & two rena filter pads (20 & 30ppi) in the first basket and ceramic media in the other two baskets. The other filter is filled entirely with pot-scrubbies...haven't been able to afford ceramics for it yet.

I've never noticed my ammonia or nitrite rise at all (not counting the initial cycle) and my nitrates stay under control (15-30ppm on average). But, lately I've had a ton of particle crap floating in my water. Looks like a thin dust cloud 24/7 & makes for a bit of a cloudy tank.

So, what I'm wondering (and currently testing) is...do I really need both of these xp3's to be loaded up with biological media? I'm really starting to think its just not necessary at all. After I finished cleaning the filters I decided to try leaving one of the xp3's off for a while. Of course I chose the one full of pot scrubbies. I'm going to keep a much closer eye on my ammonia levels than I usually do & see how it goes.

If this goes well then the next step is to see if I can take it further and only use one basket of ceramic media in the single xp3 and not have any issues. If I can do that then I can add more (and finer) mechanical filtration to the top basket of the xp3 and hopefully solve some of my particle issues. At the same time....I'd then have an extra xp3 available to use on my 65g which I'd like to set up but don't have a filter for
 
It's not an easy question to answer, which is why most people over filter their tanks. The only way I think you can find out for sure is by experimenting; slowly removing bio media and testing ammonia. Aside from that you really can't calculate how much media you'll need. And, not all media is created equal. Different media has different surface areas for growing bacteria. So how much bio filtration do you really need? Enough so that you never get an ammonia reading. :)
 
Yeah thats pretty much what I'm doing. Honestly I just couldn't think of any better thread title so I went with that :p

I really have a feeling I wont' need more than one basket of ceramic media (FWIW, its fluval branded media from petsmart...) There's a member here that vouches for running tanks without biological filtration at all. His thinking/experience is that the bacteria colonizes in the tank as well (in the substrate, on the decor etc etc) and any added bio is just overkill. Im not sure I could comfortably go to that extreme, but his .02 are a contributing factor to this little 'experiment.'
 
Moloch said:
I decided to clean my filters today which got me thinking about some issues I've been having with my setup. Currently I'm running a 90g FW planted tank thats pretty heavily stocked with two Rena XP3's and one XP1............................................................................At the same time....I'd then have an extra xp3 available to use on my 65g which I'd like to set up but don't have a filter for
Click to expand...

The easiest and most cost effecient way of getting an average running biological system running is by building your own DIY wet-dry trickle system.............I have built a standard 3-DRAWER wet/dry system for my 125 for under $60.............The pump cost me $75.99..........I stuffed the drawer with bio balls and sponges.................Constant air contact with the water ensures proper biological filtration................
 
You need enough to allow for enough nitrifying bacteria to keep ammonia and nitrite at 0. The actual amount (by volume or mass) will vary from tank to tank based on bioload (mass of fish, mass of food added daily, and temp). In the end you want much more than NEEDED to allow for room for error. A clean filter runs more efficiently than one with gunk starting to be deposited on the biomedia (which blocks off space for bacteria forcing them to colonize more on the other areas of the biomedia). You also need more bacteria based on how efficiently they are working (temp, oxygen level, food supply/flow rate, etc.).
 
There's a member here that vouches for running tanks without biological filtration at all. His thinking/experience is that the bacteria colonizes in the tank as well (in the substrate, on the decor etc etc) and any added bio is just overkill.

Though I`m not alone in this, that is my position and experience.
As suggested, I removed smallish amounts of the bio specific media from a pair of cans.
Keeping a close watch on any adverse conditions.
When I got to 3/4 of the media gone, without a problem, I bit the bullet and pulled it all.
Still no problem.
Not rocket science.
If you can pull out all your bio media without any effect to your water chemistry, the bacteria were heavily colonized in the tank, eh.
This isn`t true for everybody, nor do I suggest people start dumping their media.
Just saying, there are a very large number of tanks running a bunch of bio specific media that is doing not much.

Tiny particles in your water can drive a guy nuts, for sure.
The only answer for me was micron rated media.
Getting decent amounts of water going through a less than 50 micron media can clear a tank overnight, with the right amount of flow and circulation.
Right now, my filters are a pair of 8 micron cartridges in HOT250s, on an overstocked 55g, Mbuna tank.
Not a bit of bio media in filtration.
Water stays crystal, other than the cloud of poop when the mob goes into chase mode.
I clean the filters on a rotating schedule, getting a bit less than 2 weeks before service.
They only went close to a week when first changed filtration, but the longer they ran the clearer the water got and cleaning intervals got longer.
 
That is true, if you wean the bacteria off of the media. Without enough biomedia they will colonize any surface in the tank. Remove it slowly and they will colonize other surfaces without any issues. However, this does NOT mean that there was not a significant amount of bacteria on the media before he started. Other situations have demonstrated that effectively all of the bacteria can be on the media. I have moved tanks multiple times by moving the livestock and the filters together (no substrate, decor, etc.) and there was no re-cycle or mini-cycle. This shows that effectively all of the nitrifying bacteria were in the filter (not spread out evenly on decor, substrate, etc.). So although you can manage to get rid of biomedia, which may or may not turn out as well long term, it doesn't mean that is not the ideal place for the bacteria to grow.
 
Both good points, and Kaiser you're definitely the guy I was referring to :P

I don't think I'll ever completely get rid of the media, its far too useful for tank moves, new tanks etc etc. I do still have my magnum hot250 with with whatever the stock micron filter is (I think its 1 micron?). I can soak the thing in bleach overnight & then clean it in the sink, and it'll only run for a day or so before the flow slows to a trickle. Its also a HUGE pain in the ass to get to the stupid thing on my current setup (backed against a wall, no good side access & the canopy makes it just about impossible to get at it from the top). Hopefully when we move sometime in then next couple weeks I'll be able to position so that I can get to the back of the tank & service the filter easily. If I could get it to run for a week or two between cleanings & do a good job of polishing I'd be ecstatic. At that point I would probably leave more ceramic media in the xp3.

I made this post yesterday at 4:40pm, that was RIGHT after I did all the filter maintenance. Its still running with just the xp1 (with one 30ppi & 1 20ppi pad) and the xp3 (prefilter media, 1 20ppi 1 30ppi & ceramics) and the water is SIGNIFICANTLY cleaner. That just goes to show that I need to be a little more diligent about keeping my filters clean. Now I have a handful of particles floating around, but not the dust-cloud that I had before. If this level of clarity keeps up all week & my ammonia levels never rise then I'll be 80% satisfied with just the xp1/xp3 combo. After that I'd go ahead and add another set of pads to the xp1 to fill its basket. I might get rid of the prefilter media...I'm not really sure that its actually doing anything useful. If I do I'd replace it with more 20/30ppi pads, I feel like those are the bread & butter of my mechanical filtration.

We'll see how it goes I guess.

What cartridges are you using in your magnums?
 
Man, only a day before the micron cartridge clogs.
That be a bunch-o-gunk free floating.
It purports to be an 8 micron sieve size and have no reason to think otherwise.
Not sure what is so radically different with your tank, when I can get close to 2 weeks on my cartridge.
Even when I first got the filters running I could get a week before flow was noticeably lower.
Anyway..water clearing up is always good news, however it`s done.
 
Could be that I'm not cleaning it well enough? You just soak it in a bleach solution overnight then rinse it off with tap water?

I'll try doing that again soon now that things are generally cleaner anyways, see how far it goes. There WAS a TON of free-floating crap in the tank last time I put the magnum on it, so much so that it wasn't even really noticeably cleaner by the time it clogged.

Another thing I might try in the future when I get some extra money budgeted in is going back to that whole-house filter we talked about in another thread a while back. I never got it working last time because I was trying to do all that crazy crap with the gravel-vac. I think if I just made it a regular closed loop with a pump it would work fine with the pre-fab micron cartridges it comes with. That way I also wouldn't have to worry about getting to the back of the tank to service the filter.
 
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