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FAQs on Freshwater Aquarium Wet-Dry Filtration

Related Articles: Freshwater Filtration, Know Your Filter Media, A Concise Guide to Your Options by Neale Monks, Power Filter Impressions,  A review of some popular mechanical filtration systems by Steven Pro,  Canister Filters By Steven Pro, Setting up a Freshwater Aquarium, Tips for Beginners

Related FAQs:  FW Filtration 1, Biological Filtration, Establishing CyclingFW Sponge Filters, FW Canister Filters, FW Hang-on Filters, Ultraviolet Sterilizers, Chemical Filtrants, Diatom Filtration,


Trickle filter pads  8/27/11
Hi Wet Web Crew
I first wanted to thank you for your support and help for my previous
<You're welcome.>
After doing a lot of searching on your site I still have not been able to find an answer to a question I had.
Anyway, I have a 300 gallon African cichlid tank with a 80 gallon wet dry sump that has two 2" drains emptying into a filter pad before it trickles into the bioballs. I am planning on having 1500 gallons/hour flow rate into the filter. I have read on your site that Emperor Aquatics gravity felt filter bags are very effective at removing solid waste.
<Can be. But really, anything that incoming water flows through will filter out faeces and detritus. The question is how easy it is to remove and rinse such media.>
Would it work to attach one Emperor Aquatics gravity felt filter bag to each bulkhead draining into the wet dry sump and having the bags lying horizontal on top of a finer mesh size filter pad?
<If ahead of the biological and chemical media, then yes.>
Could I remove the filter pad below and just use the Emperor bags instead?
I know I will need to remove these bags daily and replace with clean ones. I believe the filter bags operate most efficiently in a vertical position but wanted to know if my idea would work with them positioned horizontally on the trickle plate and with or without a filter pad below.
<Obviously you need to maximize the surface area of media reached by the water. So a horizontal pad will generally work better than a vertically-aligned thing, only because the horizontal pad "meets" more incoming water. You do need to make sure any mechanical media is BEFORE any biological or chemical media.>
I also had a question concerning using two smaller Iwaki return pumps to get a 1500gallons/hour flow rate for redundancy purposes or to just use one large Iwaki pump and have another large Iwaki pump for backup.
Thanks again for your time and assistance and have a great weekend!
<Cheers, Neale.>

AGA MegaFlow Sump Model 3: Wet dry filter with Bioballs & Ceramic Stars- Anaerobic vs. Aerobic Products   5/5/10
Hello WWM crew! I finally have a question that has not already been asked and answered. Your website has been such a great resource since establishing my aquarium(s) a few years ago.
<Good to know.>
Today, my question pertains to my drilled 110 mixed African Cichlid aquarium. There is a minimal amount of crushed coral as substrate, and copious amounts of rock work, both natural and plastic injection molding.
I will spare you the inhabitants, as I do not believe it is contributing to my problem, although I will mention that my tank is not considered "overstocked". I have an AGA MegaFlow Sump Model 3. In the sump, I use a return pump rated at 1000 gallons per hour, but once the water is lifted to the 5 foot return height, is pushes closer to 750 gallons per hour. After research, I have learned that the MegaFlow 3 sump can handle about 600 gallons per hour, so I use a ball valve to reduce the flow to very close to the 600 gallons per hour figure. If you attempt to push any more water through this sump, it clearly lets you know that you are exceeding the limits by operating with a loud gargling sound and the water levels do not remain level.
About 12 months ago, I mentioned to my LFS that I was having a problem with my Nitrate's constantly being above 40 ppm.
<Too high for cichlids, as you know.>
According to the publications I have read, nitrate removal is directly proportional to the amount of water removed (assuming the replacement water has 0 ppm nitrate).
<"Removal" isn't the word I'd use; more "dilution". If you have 40 mg/l nitrate, and then do a 50% water change with 0 mg/l nitrate water, you get 20 mg/l nitrate overall. While nitrate removal is possible in freshwater aquaria, it's rarely cost effective. Fast-growing plants are perhaps the only practical approach.>
Even after a 50% water change, I would notice that my nitrate would reduce, but not by the amount the formula would dictate.
<Meaning? I assume you mean as explained above? Do bear in mind nitrate test kits may not be especially accurate. You can take it as read that if you dilute the aquarium 50% with nitrate-free water, then the nitrate level will drop by 50%.>
I checked my public water, 0 ppm of nitrite and 0 ppm of nitrate. After a period of 5-7 days, my nitrates would spike back to above 100 ppm.
<I see. But does the nitrate level go down *immediately* after water changes?>
My LFS offered a few options. First, they recommended the use of SeaChem's Purigen, which I have been using for 12 months, having recharged the Purigen twice.
<Expensive, and generally overwhelmed by cichlids. Chemical removal of nitrate is only cost effective in situations where nitrate is carefully limited already, e.g., in reef tanks. In busy freshwater tanks, you're
dumping far more protein into the system, and there's far less natural denitrification -- i.e., live rock, DSB -- going on as well.>
They also suggested that mature bioballs can become "Nitrate factories", but I have read the comments on WWM that disagree with this statement.
<Indeed. It's complex. Some authors have argued that biological filters, particularly canister filters, become "nitrate factories" because the ecology of the bacteria inside them somehow generates higher levels of
nitrate than expected. Personally, I'm skeptical of this because it doesn't make much sense biologically, and I'll make the point here that I actually do have a BSc and a PhD, so I'm not speculating out of nothingness. Nitrogen is needed to make nitrate, and the source of that nitrogen is fish food via livestock. Nitrogen fixation from the atmosphere, as happens in the wild, isn't happening in aquaria at any appreciable rate, except perhaps among blue-green algae. So, provided a biological filter is cleaned and maintained properly, there's no possible way it could magically generate nitrate above and beyond the supply of nitrogen via fish wastes. In other words, if you add 5 grammes of nitrogen per day, you'll get 5 grammes worth of nitrate, whether you're using a canister filter, a sponge filter, or an undergravel filter. Cleaning is important because some detritus takes a long time to break down, so in theory you could have, for example, dead leaves in the filter that over several months eventually break down and add more nitrogen to the system, but if you let your filter get that dirty anyway, you'll have other problems as well because of the reduced flow rate!>
They recommended changing bioballs for ceramic stars, as used in canister filters.
<Won't make the least difference.>
I took the suggestion, and bought two small packs of ceramic stars and replaced an equivalent number of bioballs. I would estimate that my wet dry is now filled with approximately 85% bioballs and 15% ceramic stars.
Here in lies my question:
After additional research, I learned that ceramic stars are used in a canister filter because of their supremely porous nature providing a tremendous amount of surface area for bacteria to grow (in anaerobic reactions).
<In theory that is the case, but in practice virtually all the filtration inside canister filters is aerobic. To get anaerobic, nitrate-reducing filtration, you need extremely slow flow rates, hence the need for things like DSBs and live rock.>
I have also learned that the bioballs are the surface for bacterial colonies that will be acting in aerobic fashion in my sump. Can using ceramic stars (if they are designed for anaerobic bacterial colonies) in an
aerobic setting cause nitrate spikes?
<Can't see why.>
How else can I remedy the situation? Diatom?
Fortunately, I monitor the tank closely for the inhabitants sake. I feel that if I cannot get the nitrate's down to at least a reasonable level, I will begin to notice the long term affects on my fish, and I really do not want to contribute to their stress, declining health, or eventual death<I'd look at other factors. Filter maintenance may well be an issue, but otherwise concentrate on reducing the nitrate going into the system via water changes, and on reducing the nitrogen going into the system through limiting food supply and stocking density. If you're keeping Tanganyikans and some Malawians, plants can also make a big difference; under bright light fast-growing species such as Vallisneria will be using up considerable amounts of nitrate. A freshwater DSB may also be an option;
see the recent issue of 'Conscientious Aquarist' elsewhere on this site for more.>
Thank you so much in advance for any assistance that you can offer. I am happy to try solutions to remedy the situation.
Jeff S.
<Cheers, Neale.>

FW wet dry... New World Cichlid filtr.    2/9/10
Hello there,
I am in the process of setting up a 135 gallon fw tank. I have a fairly large Oscar, a jack Dempsey, and a large Pleco. I am planning on getting them a few more tankmates once the tank is up and running. I am also planning on having plenty of live plants throughout the tank. I have some aggregate gravel as my substrate. I am building a wet/dry filter and just had a few questions. I am setting it up very similar to the Eshopps 150-cs, but I was curious as what I should use for mechanical filtration. A few of the sources I have read on the internet say polyfill is the best, but I wanted to check with you guys before I made a purchase. Any suggestions would be very much appreciated. Thank you very much for your time.
<Yes, a wet/dry filter will work. However, the reason they're rarely used in freshwater tanks is that they drive off carbon dioxide, and that makes it difficult for plants to grow. Floating plants will be fine though, since they get their CO2 from the air, and given Oscars and JDs uproot plants anyway, that's likely the way you'd have to go. In terms of mechanical filtration, it really doesn't matter what you use. There's no "best" really with mechanical filter media, since anything fine enough to trap silt will do. Mechanical filters are let down by how often *you clean them*, since
they're only as good as the last time they were rinsed off; leave them clogged up with silt for a couple of weeks, and they won't do anything at all. So choose something easy to clean and (if necessary) cheap to replace.
Cheers, Neale.>
Re: FW wet dry
If that is the case then what would be a more appropriate method of filtration?
<Well, depends what you're after. Since Oscars and JDs dig, and Plecs can be pretty hard on small plants, your best bets in terms of plants for the bottom of the tank will be Anubias, Java fern, and if you can get it, Bolbitis. All three are slow-growing, so have little impact on water quality or algae control, but they are pretty and difficult for fish to destroy (Java fern in particular seems to taste horrid, so most fish ignore it). Most critically, they are grown attached to rocks and bogwood, so won't be bothered if your cichlids dig up the sand or gravel. If they get moved about, that won't bother them either; just put 'em back where you want them, or move the plants around so your fish have territories. Throw some floating plants into the tank for algae control, and you're all set.
Anyway, if you grow these, you're able to use a reverse-flow undergravel filter, which is perhaps the best all-around filter for large fish. Unlike other filters, these have water pushing UP through the gravel, and this moves faeces and detritus into the water current, and then the canister filter can remove them easily. So you get good water quality PLUS good water clarity, without having to constantly clean the gravel. Having said this, because cichlids dig, they can "short circuit" undergravel filters of all types, so you will need to place a gravel tidy under the top half inch or so of gravel, so that the cichlids can do minimal damage to the filter bed. If this doesn't appeal, and you really do want live plants, then the best filters are those that "splash" the water the least, since the splashing is what causes the CO2 to be thrown out. Plants with roots hate undergravel filters, so that's another issue too. Regular canisters are perhaps the best, since these can be rigged with spray bars just under the waterline, so they ripple the outgoing water rather gently. The downside of course is that the less circulation of the water there is, the happier the plants will be, but that's the reverse of what big cichlids want. It's perhaps best to think about what sort of aquarium you want: an underwater garden, or a community of cichlids with just a few plants as a backdrop.
There are some cichlids that love plants, including (surprisingly to some) quite a few Malawian and Tanganyikan species that live in the vegetated parts of these lakes, often around beds of Vallisneria. Since Vallisneria is remarkably easy to grow, and comes in a variety of colours and sizes, that can be a nice way to combine cichlids, plants, and a few catfish.
Cheers, Neale.>

Wet Dry filter media for cichlid set up   11/25/09
Greetings Crew, may I ask you a question in regard to biological filtration?
I am planning an African cichlid setup. The display tank will be a 125 gallon with a 40 gallon sump. I am leaning toward a DIY wet/dry filter in the sump. Could you please suggest the best media to utilize in a wet/dry application and how much I would need for proper biological filtration?
<For such a set up, a good deal of carbonaceous rock and a deep sand bed of finer sand (4-5 inches of nominal 1/16" diameter) will be best here. All submersed, that is no plastic media necessary>
I have looked at bio balls and have loosely figured on five gallons. I am also hearing that better bio media is available now a days. Any help is very welcome. Thank you Mark
<It is... Please read here: http://wetwebmedia.com/bioballfaq2.htm
and the linked files above. Though this section deals with marine systems, the principles are the same for freshwater.
Bob Fenner>

Freshwater sumps  11/28/2007 Hello again. You have been very helpful so far and I feel bad about pestering you for info but again there seems to be a lack of info on this subject. I am converting from marine to freshwater (most people go the other way) and have a sump which I want to use with this system. The tank is about 500ltrs with a 100 ltr sump. My question (to finally get to the point) is what would you recommend to put in the sump. Currently the first section is bio balls, then miracle mud with colerpera (sorry about the spelling) and finally live rock with a live sand bed. I know the live sand will 'die' and the live rock would be a waste. I was thinking about keeping the bio balls but replacing the mud with gravel and some sort of plants. The main section was to be changes to gravel. Have you any suggestions with what I am proposing. Any help gratefully received. Many thanks Paul. <Hello Paul. Unless you're keeping a hard water aquarium for, say, Tanganyikan cichlids then don't leave anything calcareous in the sump. For a standard community tank or similar, then opting for biological filter media of some type is probably the way forward. More bio-balls or some sponges would work well. Because nitrate control in freshwater systems is both easier (plants, water changes) than in marine tanks and less critical (freshwater fish largely nitrate-tolerant) there's no real need to provide denitrification in a freshwater tank. But some people have very effectively used 'vegetable filters' and 'algal scrubbers' as part of the filtration system, by placing fast-growing plants/algae into a brightly-illuminated chamber. There's a book called "Dynamic Aquaria" that discusses these, among other such esoteric topics. While hardly a book for the casual aquarist, it's an interesting read if your library has a copy. Basically the idea is that you optimise plant/algal growth, and then crop the plants (even daily!) effectively removing wastes in "solid form". Some freshwater plants, such as Cabomba and various floating plants, will grow incredibly rapidly if provided optimal conditions. I hope this helps, Neale.>

Bio ball alternatives in freshwater  -- 05/08/07 Hi team, <Greetings!> I would like to know of any ideas for my wet/dry driven 125g planted loach tank. I have read lots of ideas on the salty side of things, but don't know if these ideas would translate into freshwater. <Essentially similar to marine aquaria except you don't have the option of living rock. Standard protein skimmers are only viable in brackish water tanks at SG 1.010 upwards. There have been freshwater skimmers invented from time to time, but as far as I know none have become inexpensive commercial products.> Right now I have 6 clowns that are 4-6 inches and 5 boesemanni rainbows and assorted tetras. I am currently running bioballs and about 4.5 lbs of sintered glass in my sump. Any ideas on nitrate reduction? <Generally speaking nitrate management in freshwater tanks is easier and less critical than in marine tanks. With a few exceptions (such as mollies and Tanganyikan cichlids) freshwater fish are fine with even fairly high nitrate levels in the 50-100 mg/l bracket. Why nitrate is easier to manage is that doing large-scale water changes is easier and less expensive than in a marine tank because you don't need to add salt. Under most circumstances, one or two 50% water changes per week will maintain excellent water quality. Finally, the use of fast-growing plants removes nitrates quickly. Floating plants and fast-growing stem species like Cabomba, Vallisneria, and hornwort are recommended for this. Under good lighting (3 or more full-length fluorescent tubes) these plants will be growing so rapidly you will cropping them on a weekly basis. In the process of growth they remove nitrate and suppress algae (in part through allelopathy).> Thanks, CW <Cheers, Neale>

Wet/Dry filtration in freshwater system  11/16/06   I recently converted my 75 gallon SW to freshwater.  In doing so, I returned my bio-balls to the Wet/Dry Sump.  Is this necessary, or will it add to higher nitrates, or other problems.  If I remove them, should I put anything in the sump. <Is about as "necessary" and of use as with/in marine applications... I would remove them again once this system is firmly establishes>   Also, I believe I read somewhere on the site that live plants are not recommended with a trickle filter-wet/dry set-up.  Is there a way to successfully keep live plants in my system.   Thank You! <Mmm... should not matter (much) here... though... as many such truly aquatic plants can/do use ammonia/ium directly as a source of nitrogen... and the boosted nitrification from the WD too readily removes this... I would wait on adding much in the way of plants till after you've removed the plastic media. Bob Fenner>

FW Wet-Dry, Af. Cichlid Sys....   7/8/06 Hi <<Hello, Rene. Tom>> I'm getting a 125 gal. tank with a wet dry filter system. <<New or "pre-owned", Rene? Information sheets contained with a new system will have the manufacturer's recommendations for cleaning/maintenance of their particular filter.>> Currently I have African cichlids. My question is what is the best maintenance? How often do I have to clean it? <<I state the obvious here but the "best" maintenance is that which keeps the mechanical filtration media clean and free of built up solids along with maintaining a healthy supply of beneficial bacteria in the bio-media. Some wet-dry filters come with built-in protein skimmers, which will fairly ineffective for a FW system. As far as how often to clean it goes, this will be largely experimental on your part but I would recommend cleaning the "pre-filter" media on a monthly basis to start. Wash this out in used aquarium water (optimal) or in tap water that you've prepared with a dechlorinator (less optimal). The frequency will, of course, depend on the load your fish place on the filter based on number of fish, sizes, feeding habits, etc.>> Do I remove all of the filter media and replace it? <<No. The pre-filter will ultimately need to be replaced as this will probably break down over time but the bio-media need never be replaced short of a calamity in the tank. Depending on the type of filter you're getting, this bio-media may be plastic, ceramic or some other sort of material and will house your beneficial bacteria. Replacing it would throw your tank into a "tailspin" toxin-wise, which is why you should rinse it - again, in used tank water - and put it right back into service. Provided you keep your pre-filter in good order, cleaning the bio-media of built-up solids shouldn't have to be done very often. As I've mentioned, hopefully you'll have access to the manufacturer's recommendations. Eheim, for example, makes a wet-dry filter system wherein the foam pre-filter should be discarded after about a couple of months. The mechanical and biological filtration is left to the other media contained in the canister after this time.>> Any suggestions will be much appreciated. Rene <<Hope I've given you enough to go on, Rene. Enjoy your new set-up! Tom>>

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