How Do Undergravel Filters Work With Air.pump

INTRODUCTION:

Fish, similar any other animal, have in food, water, and oxygen to maintain their metabolism and life.Â They also excrete solid and dissolved wastes.Â Those wastes are toxic to the animals that produced them.Â In the wild wastes are rapidly diluted past the much greater water book to fish ratios in that location than those we use in out tanks.Â We are effectively concentrating the waste cloth, so we have to ensure that we can detoxify the waste material in some manner.Â There are bacteria that are delighted to take fish waste and use it as their own food/free energy source.Â The main toxic nitrogen-containing waste matter production from fish is ammonia (NH3), or ammonium ion (NH4+), dependent on pH and temperature.Â Certain bacteria absorb ammonia/ammonium ion and get energy by oxidizing it to nitrite (NO2–).Â They release the nitrite as a waste.Â Nitrite is as toxic equally ammonia, or more and then.Â Other bacteria take upward nitrite and oxidize it to nitrate (NO3–), releasing the nitrate into the h2o.Â Nitrate is relatively non-toxic at depression concentration.Â Both of these types of bacteria must live attached to a substrate, a surface.Â The largest surface area in our tanks is not the glass, only the gravel.Â The desired leaner also crave oxygen in the h2o, and as they are attached, water currents must bring the oxygen to them.Â The same currents will bring them "nutrient" in the grade of ammonia and nitrites- a adept life if you are a nitrifying bacterium.Â Current can merely penetrate a modest distance into most gravel beds.Â Oxygen tin penetrate by diffusion, simply this is a much slower process than by current.Â This limits the oxygen- and food-rich sites to very almost the surface.Â Okay, suppose we could suit to accept a slow current flowing through the bed, we would accept the entire surface of the gravel open for bacterial colonization.Â From such thought came the undergravel filter.

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CONVENTIONAL UNDERGRAVEL FILTRATION:

An undergravel filter (UG) is a slotted plate that fits the bottom of the tank, on acme of which is a layer of aquarium gravel.Â There are several ports on the plate where vertical riser tubes may be placed.Â Originally all UGs were driven past airlift. The earliest units used only the rigid airline itself.Â A scrap afterward, an airstone was attached to the end of a piece of rigid airline tubing and lowered into the riser.Â To operate an air-driven UG, the output from an airpump is directed through a gang valve (to command and balance air volumes) from which individual lines can run to each UG riser.Â The airstone in the riser is best placed just higher up the neckband connecting the riser to the UG plate itself.Â This avoids the possibility of air beingness pumped under the plate, which could block operation.Â The bubbling from the airstone (the smaller the better) rise to the surface and out across the water surface.Â The cavalcade of air + water in the tube is lighter, weighs less, than an imaginary equal column of water alone would weigh.Â Since the temper is pressing downwards equally all over the surface of the tank, the air-h2o mixture in the column moves upward due to atmospheric pressure and gravity trying to equalize the riser air-h2o mixture and the tank water.Â Air is constantly pumped into the riser, then they cannot be equalized.Â H2o moves from the tank through the gravel and UG plate and upward the riser in constant circulation.Â Simple and constructive, the slow current provides enough oxygen and "food" (ammonia and nitrites, not fishfood) to the bacteria.Â

Airstones clog and need regular replacement. Air bubbles are noisy (I object to that). They splash the embrace glass, leaving behind mineral and protein films that can eventually etch the glass. In the short term this h2o and mineral promotes algae growth on the underside of the drinking glass. It tin too contribute to salt/mineral creep onto cover glass and the tank rim. I object to all of these things. I object to about things that make noise, and to anything that makes another task for me.

More modern installations use a powerhead (an electrically driven water pump) on top of the riser and omit the air, airstones, etc. The pump draws water from the riser and pushes it across the water surface, or more commonly, nether the h2o surface. This tin increase the flow tremendously, depending on the gallons per hour rating of the pump, the thickness of the gravel bed, and the particle size of the gravel. Please don't child yourself that a pump rated at 300 gallons per hour is actually going to move 300 gallons through your gravel every hour. Pump and filter ratings are done with no load and at zilch head. They represent the maximum possible output, not a real-world application. The pump has to overcome friction and inertia to move water from the tank down through the gravel bed and the slots in the UG plate, across the tank bottom and up the tube. The type of pumps we use "push" improve than they "pull", and nosotros are asking them to pull in this application. Not a big deal, they do the chore quite well. It is highly questionable if large flow rates are fifty-fifty desirable, but I'll argue that bespeak later. Pumps crave much less upkeep than airlifts. They do need to be opened and cleaned at intervals of a few months minimum to maintain their menstruation rate. This is easy if you have a selection of small "bottle brushes" for cleaning out the impeller housing, intake, and outlet. Many powerheads have venturi openings on the outlet side of the pump. If desired, a piece of tubing can run from the opening to higher up the water surface. Air is sucked downwards the tube and into the outlet stream of h2o (the venturi issue is strongly reduced pressure at right angles to the direction of menses). Call up the noise of the airlift? This is much louder. Think the films, algae, and mineral creep of the airlift? This covers a larger expanse, then to me is worse. Do you demand to ask if I E'er use the venturi of a powerhead? Well, not for air, thank you lot. If you have a current of water from a powerhead or other filter return running across under the surface of the water so that it ripples the surface without breaking the surface, you volition provide sufficient aeration to the water.

Gravel size does matter for use with an undergravel filter, but it is pretty straightforward. Surface expanse per unit weight is inversely related to particle size- the smaller the average particle, the more surface at that place is in a pound of particles. Very small particles (sugar sand) will restrict flow and sift through the plate, and so that is out. Somewhat larger sizes are used often by plant growers, as many plants adopt a bit finer particle size than standard aquarium gravel, only plants are not recommended with standard UGs. Standard aquarium gravel is fine for UG. Larger gravels, such as pea gravel, are not good, as yous are losing surface area. Big gravel is harder to keep make clean besides. Nutrient and fish waste tin can fall between the gravel particles and be hard to go out (hydrovacuums or gravel washers equally function of vacuuming the substrate, like UG plates, were designed for standard gravel). Fifty-fifty worse, it may go through the gravel to the plate and build upwards on the floor of the tank. A gravel bed of one to two inches depth is standard. Deeper beds may restrict menstruum.

Most of the controversy associated with UGs is related to maintenance. UGs operate best as biological filters. They unfortunately serve nicely as mechanical filters equally well, especially in tanks using loftier-output powerheads. Such pumps do motility a lot of water through the bed, then they can trap most particulates out of the water column. This pleases the tank keeper, because the tank looks clearer and cleaner. Fine, but as is the case with any mechanical filter, the tank is not really cleaner, the droppings has been removed from the water column and deposited in the filter. Here, the filter is the gravel. Microorganisms of various sorts will digest the material eventually, but you are building up decomposed waste in and eventually under the gravel bed. Untended gravel beds in UGs are bombs waiting for critical mass. Nitrates in such tanks tend to be elevated or astronomic, simply about people don't test for nitrates. On the other manus, if UGs are maintained properly, they can run for years with no problems. Proper maintenance is non complicated or difficult.

I am a firm laic in water changes. H2o is cheaper and easier to work with than carbon, analogousness resins, filter cartridges or flocculants. My tanks are partialed routinely. For me, a i-third to one-half change every calendar week is no big deal. Others may prefer some other change level, fine. Pick a level that is comfortable for you, do it until it becomes addiction. While you are still developing the habit, examination for nitrates – before or after your water change doesn't affair and then long as y'all are consistent. Record the results – I use calendars: MR1 (proper noun of tank) NO3: 10ppm. The side by side week: MR1 – NO3 >10ppm. The calendar week following: MR1 – NO3 >>10ppm. The terminate of the month: MR1 – NO3: 20ppm. Hmm, there is a trouble here. The nitrates are rising with time. I demand to a) reduce the stock, b) feed less, c) change more h2o. I'thou happy with the tank as is; I don't remember I overfeed, so I'll get-go irresolute twoscore% per calendar week. The next month I see: MR1 – NO3 <20ppm, MR1 – NO3 >10ppm, MR1 – NO3: 10ppm. Problem solved. I'm happy, the tank is happy, and the tank is cleaner than it was. If this increase had not done the job, I would accept moved the percent h2o alter up once again. Note – in that location was no visible modify in the tank. If I had continued the smaller changes, the tank would have continued to refuse imperceptibly. I could take experienced less agile fish, algae outbreaks, perhaps disease outbreaks. Information technology is best to solve your problems before they become issues.

That was the long wearisome curve. The fast break is that is that water changes are how you make clean UGs. While yous are siphoning (or Pythoning) water from the tank, y'all use a hydrovacuum on the gravel. If yous practice pocket-sized regular changes yous may not be able to vacuum the entire substrate in one fractional. Again not a problem- starting time at the left (or right, your choice), work front to back, and when you lot have removed every bit much water as you lot wanted, mark your identify with a modest stone. Next time showtime at the stone and proceed. Continue re-marking your identify until you've covered the tank and first over. This is simple, no-brainer work. If yous let the UG to get without vacuuming for months, and so clean it, you will take a major job. Y'all may also reduce the functional chapters of the biofilter. When the gravel is vacuumed regularly, the bacterial flick on the gravel will stay young and healthy. A neglected filter may take more bacteria living on the particulates between the grains of gravel than on the gravel itself. This is so because the bacterial motion picture on the gravel volition have been smothered past debris, or simply have peeled off the gravel from its own over-growth. Vacuum that bed and yous may cut your handling capacity. If you have a neglected bed and I've inspired you to clean it before it crashes, clean 1/four every two weeks, or 1/3 every three weeks. Afterwards that you can clean as much every bit you can cover during your regular h2o modify. The other adventure of neglected UG beds is build-up of debris under the plate itself. With regular maintenance, this is unlikely to occur. It may occur nether a bed made of oversized gravel matched with an oversized powerhead. In a neglected bed it is inevitable. Y'all can attempt siphoning from nether the plate with flexible airline tubing fed downward the riser and nether the plate, but I'm uncertain of the effectiveness of this technique.

What tanks should Non use conventional undergravel filters? There is a short but clearly defined list:

1. Substrate-spawning cichlids or other fish with major earth-moving tendencies (some large cats) are incompatible with conventional UG. They dig and short-circuit the water flow.

ii. Fish needing or requiring fine to very fine sand [rays, flounders, many "eels" (Mastacembelidae), some catfish, elephant-nose] in which to bury themselves or forage for worms and crustaceans are non suitable for UG, as their substrate will go through the UG plate.

3. Constitute tanks are not suited for this technique. Most root-nourished plants may non perform as expected over UG plates, and enriched substrates are incompatible with the technique. There are exceptions to this rule, simply they would be for avant-garde hobbyists. Somewhen there may be another article on that topic. Plants in pots are unaffected by UG of form.

4. Any tank belonging to a fish keeper who is unable (for any reason) to perform regular maintenance. If you are the blazon of hobbyist who must or does ignore your tanks (except for sporadic feeding) for weeks to months, then goes into a mad flurry of tank cleaning, UGs are not for you.

REVERSE-Period UNDERGRAVEL FILTRATION:

It is possible to avoid the biggest problem of UGs, their excellent mechanical filtration potential, past reversing the flow. That is, instead of pulling the h2o down through the gravel, you button it up through the gravel. You likewise apply a sponge pre-filter on the powerhead, so it is pushing pre-filtered h2o down the riser tube, out under the plate, and up through the gravel. This is opposite-flow undergravel (RFUG) filtration. Several brands of powerheads can be adapted to this, but I merely have personal experience with i, Penguin, which offers an accessory kit to convert their conventional pump to opposite flow. The kit has an elbow attachment to mate the pump output tube to the riser tube and a sponge assembly for the intake side of the pump. This is non expensive, and being a lazy human being, I oasis't tested any other technique since these came on the market. The sponges are hands removed for rinsing under the tap. There is no concern with preserving whatsoever nitrifying bacteria in residence in the sponge, every bit the gravel bed is to perform that service. The sponge can role purely as a mechanical filter, and be rinsed weekly, biweekly, or whatever your h2o modify interval may exist. I similar biweekly at to the lowest degree, weekly is better, to get waste product out of the tank before it is completely digested in the system. The gravel is still hydrovacuumed, but yous will exist astonished at how petty fabric comes out of the gravel compared to conventional flow UG, or to conventional substrates.

At that place are other powerhead brands that take diverters congenital into the intake side to reverse flow. In my feel, the reversed catamenia with these units is a small fraction of their normal rated period. You are running substantial power consumption and not getting much output from it.

RTR'Southward ULTIMATE OVER-ENGINEERED RFUG:

Having removed the chief objection to the technique, nosotros have the trouble of digging fish to resolve. It tin can be done, but is DIY and MUCH more setup work than either straightforward UG or RFUG. At the time of evolution of the particular technique I was convenance several substrate-spawners. I despaired over having the tanks a) wait decent, b) be easier to maintain, and c) not have blank glass areas on the lesser.

There had been an article long agone, in FAMA I believe, on using floss under the gravel itself over conventional UG plates (my apologies to the writer, I don't take the citation at hand). The object of the practise was to increase the sites available for colonization. Okay, there is more surface to a mat of cobweb than to a gravel bed, just I was concerned nearly clogging the mat with gunk over fourth dimension, compression of the mat by the overlying gravel, and the Cichlids could still uncover the mat, with double or more gravel depth elsewhere. This would upshot in uneven flow and potential loss of role.

Enter eggcrate light diffuser. This is a plastic grid, 1/ii inch or less thick, used in some commercial fluorescent light fixtures. It is bachelor at hardware stores and plastic suppliers in 2 10 4 foot sheets. So, cut a piece of eggcrate with about I/two inch clearance from the front and side walls of the tank, cut out notches to allow the UG plate riser collars to protrude. Then cut another piece just like it. Cutting a sheet of filter floss with less clearance than allowed for the eggcrate, say 1/4" front and sides. If I am working with a tank that is a close fit for the standard sheet size, I don't bother to trim the 1/4" inch off, gravel will conceal it. Brand brusque straight cuts in from the back at the location of each riser neckband, and then a crosscut out from that to the edge of each collar. This is in effect a "+" with one leg anchored at the back of the floss. I apply Marineland'due south bonded filter pad, which is available in 12 x 24" sheets. Information technology seems the well-nigh uncrushable of the types I've tested. If you have a dissimilar favorite flavour, by all means apply it. If larger areas are to be covered, simply butt the pieces together. Finally, cut a canvass of fiberglass window screen three" longer and 2 1/2" wider than the eggcrate panels you cutting previously.

Associates is simple. The only non-standard technique I employ is to gather with several inches of water already in the tank. Trapped air under the plate will stay there, so I brand sure that I accept all the air out from the UG plate before I continue. Place the riser tube in whichever collar y'all wish, just examination-fit the contrary-menstruum powerhead at present, earlier completely filling the tank, to be sure it fits where you desire information technology to be. Commonly the riser tub must be cut downward to a lesser height. Remove the pump and its' riser again to have it out of your way. Cap the leftover collars (without trapping air please). Spread the fiber mat and push it down around the collars. Cover that with 1 of the panels of eggcrate. Next add the sheet of fiberglass screen. Y'all desire about i 1/two" folded down over the eggcrate front and sides, almost 1" folded down at the back wall (less here as there volition be no gravel betwixt the filigree/plate associates and the back tank wall). A fist-sized stone sitting on the associates in the heart of the tank can help hold everything while you make the adjustments. When you are happy with the screen placement, cutting an X or + over the called riser collar and button downward the backlog screen. Replace the riser tube. Remove the rock and add the 2nd sheet of eggcrate. Add part of the gravel, mainly around the edges of the tank. Using a flexible spatula, dispensable plastic pocketknife, or similar tool, work gravel downward at the front and sides, alternating side to side to front frequently then y'all don't push the whole assembly askew by over-packing any one area. You are Non forcing gravel into a crevasse; you are working in just enough to conceal the eggcrate. Add enough more gravel to barely fill the eggcrate filigree. If the tank is to have significant rockwork for caves, etc., place this now, solidly on the eggcrate for support. Finally add together more gravel to embrace the eggcrate about 1/4 -i/two". Fill the tank and reposition the pump. Make sure it isn't total of air before plugging information technology in. You are in business organisation.

Maintenance is easy. Rinse the prefilter sponge, preferably weekly; at least with each h2o change except when you have minor free-pond fry in the tank- they graze the sponges and I reduce the rinses during this short period. Vacuum the gravel as usual, but y'all can't go securely every bit you actually simply take a thin veneer of gravel, your real biofilter is the fiber pad. If your fish are mounding besides much gravel in corners, just remove some. By this time yous won't be shocked to see a white grid in your gravel. I like to get out the fish some top gravel to move around, it is part of their spawning instinct after all.

If your tank is taller than a fifteen or 20L, and if yous may have a higher bioload than a spawning pair of fish and their fry, yous can double the floss layer. Cut a second sheet of floss and another eggcrate. Layer from the tank lesser up: UG plate, floss, eggcrate, floss, eggcrate, screen, eggcrate, gravel. I only dismantled a 30XH with double floss set up eleven years ago. The floss wasn't muddy. It was not pristine white, but for eleven years erstwhile it was very clean. My mbuna tank with hundreds of pounds of rocks was set up the same way. It was older than the 30XH, but it had been moved, and had to exist dismantled for the re-location. Both of those tanks were started with canisters feeding the RFUGs, but that is a real waste of a canister. Likewise, I don't like to apply canisters equally mechanical filters, they are too inconvenient to service as often equally I like for mechanicals.

What blazon of tanks should not use RFUGs? Well, at that place were four on the conventional UG list. Hither I would reduce it to two for the over-engineered RFUG. It withal isn't the best technique for plants to nearly planted-tank hobbyists, but hey, neither are nearly substrate-spawning Cichlids. Very fine sand will sift through the fiberglass screen, so it is all the same out for fish that need that. Even those folk who can't manage to do maintenance equally oft as they should are likely to be no worse off with these than with any other filter. The prefilter sponges have a pretty good capacity for property particulates, just as those are broken down they will contribute to the nitrates in the tank equally will whatsoever untended mechanical filter.

Just don't dismiss UG biofiltration out of mitt as a cheap technique for novices. Information technology can, properly fix and properly maintained, provide equally large a reserve capacity as a fluidized bed filter, a wet/dry out, or a big Eheim canister, and exercise so at somewhat to much lower price. Information technology is unfortunately a DIY technique and not off-the-shelf. Nevertheless, the skill level required to DIY is much lower than that needed to build a light hood or a tank stand.

I freely admit that I practise not utilise my RFUGs as the sole filter in any of my tanks, nor would I recommend them as sole filter, equally they provide no discernible current. On the other hand, neither do I use canisters, power filters, fluidized beds, veggie filters or algae scrubbers, West/Ds or anything else as sole filtration. ALL of my tanks other than the snail tanks (and even well-nigh of them) have at least two, and up to four singled-out filter types on them (another topic, another fourth dimension). The mbuna tank mentioned in a higher place had a sizable canister thermofilter, RFUGs, two internal canisters, and a Due west/D (more for increased water volume than filtration to be honest). I practice believe in redundancy, not often to that extent, but that 1 is an awfully nice tank and very easy to keep. I would not consider discontinuing utilise of UGs. They are also valuable to me in several applications, especially in tanks with lots of rockwork. I'm more than willing to do the extra work up front to remove the risk of anaerobic pockets effectually my base rocks at some unknown time in the future. The UG is, like whatsoever filter, a useful tool. Like any tool it tin can exist misused or abused. Certainly it is often misunderstood.

This article appeared start on another site. It has been edited and updated for this site.

Robert T. Ricketts, a.thou.a. RTR

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