Reply To: Keeping sand bed clean

Pete Giwojna

Dear Eric:

Yeah, a sandbed can get awful dirty in a surprisingly short time since that’s where all of the detritus, fecal matter, and organic debris in the aquarium accumulates.

It can be a struggle to keep a sandbed of any depth clean, and I have a few suggestions but I don’t know how helpful they will be sent it’s likely that you’ve already explored them with unsatisfactory results.

A small diameter siphon hose works well for cleaning up leftovers in a tall tank, Eric, but a dip tube is even better and will do a fine job for spot cleanups. A dip tube is just a plastic or glass tube, usually 12 to 18 inches long (the longer the better for tall tanks), with the long small-diameter tube constituting the principal part of a dip tube. There is usually a bulbous section near the bottom to increase the capacity of the dip tube, which narrows down again at the mouth. Some models have a flared mouth to eliminate picking up gravel.

To operate this implement, one finger is held over the top, tightly closing it, and trapping the column of air inside. The mouth of the tube is then placed in the aquarium directly over the dirt, uneaten food, fecal pellets, or debris to be removed. Next you remove your finger from over the end of the top part of the tube, so that the waste material is drawn up into the tube as the water rushes in and the air escapes from the top. Next you reposition your finger over the top end of the tube and remove the dip tubes containing the waste matter from the tank. The dip tube is emptied by inverting it into a container. There are also “take-apart” dip tubes which can be dismantled after use for greater ease in cleaning. A dip tube is more convenient than a siphon for removing a small amount of debris and also for working in smaller tanks.

A power dip tube is a modification of an inside filter operated from the air pump. The air-lift tube is lengthened enough to reach the bottom of the aquarium. Usually a handle is provided for convenience. For best results all the air that the pump provides should be used, as it strains water through the filtering material back into the tank. Usually only glass wool or an equivalent synthetic material is used as a filter medium.

The power dip tube is faster than an ordinary dip tube in use, but not as fast as a siphon. It is particularly useful to people who do not have a source of water suitable for fishes readily available and therefore wish to reuse what they have.

I would be wary of sand sifting gobies though, Eric. A lot of reef keepers have had nightmares experiences with them due to their habit of picking up a mouthful of sand, swimming up to the top of the tank, and then spitting it out. They will do this relentlessly and reefers tell me this quickly becomes exasperating because the sand settles all over the aquarium décor, rock work, and corals, and the fine detritus that is stirred up turns their tanks remarkably cloudy. The overall effect is to turn their formally beautiful aquarium into “an expensive snow globe.”

It is then the devil’s own business trying to catch and remove the overzealous sand sifting goby to restore order again without breaking down the entire aquarium.

If you want to give them a try, you might consider a Yellow Watchman Goby (Cryptocentrus cinctus), however, Eric. They do well with seahorses and they are usually not so relentless about their sand sifting that they create a perpetual sandstorm in your aquarium.

But a better choice might be to try some of the Sand Shifting Crabs from, sir:

‹open quote›
The Sand Sifting Crab is a small round-bodied gray crab with small digging appendages, but no true claws. These little crabs bury themselves into the sand. When feeding they’ll leave their forebody out of the sand, using two small “scoops” to catch food. These crabs are peaceful and can be kept in groups. The Sand Sifting Crab will not eat any beneficial creatures in the sand bed; they are filter feeders. They are also a great feeder food for larger fish.

Crabs belong to the Class Crustacea and Order Decapoda, which is characterized by two pair of antennae, three body parts, and five pairs of legs. The head of a Crab is connected to the thorax and covered by a shell called carapace. They have a smaller abdomen and tail compared to Shrimp and they keep this tucked beneath the carapace. The first pair of their legs are usually developed claws which they use to gather food, use as protection, and to move objects. In order for Crabs to grow they need to shed their exoskeleton, a process called “molting”, which allows them to remove their restricting shell and begin a new one. Often times in the home aquarium Crabs will leave this translucent shell in full view so it can serve as a distraction while the Crab finds a hiding place and allows its new shell to harden.

Size: 1 inch
Care Level: Easy
Temperament: Peaceful
Reef Safe: Yes
Diet: Plankton
Acclimation Time: 1+ Hours
‹close quote›

Another good option would be to consider sea cucumbers for your sandbed. Providing you can obtain the right kind, sea cucumbers are unexcelled as sanitation engineers in a tank with a deep live sand bed. They are tremendously beneficial if you can obtain the correct type from a reputable dealer that you trust.

Holothurians or sea cucumbers are echinoderms, close relatives of the starfish and sea urchins. They have the same pentameral, or 5-sided, radial symmetry as sea stars and sea urchins, which is most evident as the five rows of tube feet that run longitudinally down their long, wormlike bodies. They are simple sessile animals that have no brain, heart, or eyes, breath through their anus and often entertain houseguests therein (e.g., pearlfish , commensal crabs, and parasitic snails, all of which are allowed to nibble freely on their innards) and routinely disembowel themselves in response to stress. Their mouth is located at the opposite end of their bodies from the busy (and oft crowded) anus and is surrounded branching, sticky, mucus-coated tentacles, which can lengthen or shorten dramatically, and are used to sweep or mop up the substrate, gather up all manner of dead or decaying organic matter, and pass it into their mouths. Basically, they consume organic detritus and ingest fine-grained sands and sediments to digest off the bacteria, microalgae and diatoms that cover the surface of each sand particle.

The beneficial Aspidochirotiacea sea cucumbers that make useful aquarium janitors feed by burrowing into and ingesting the sediment, digesting what is edible from it, then excreting the rest. Cucumbers with this type of feeding technique make good sand stirrers and substrate cleaners. As they burrow through it, they continually swallow the silt and sand, extracting animal and plant remains as the sediment passes through their intestines. Dirty sediment goes in, clean sediment comes out. Their excrement is therefore clean and relatively nonpolluting. Feeding is a full-time occupation and nonstop operation for these burrowers, and they can process an incredible amount of sand through their intestinal assembly line. It is estimated that a single sea cucumber digests, filters, cleans, and expels up to 45 kilograms of seabed a year in this manner! Suffice it to say, there is no need to vacuum your sand bed if it houses burrowing sea cucumbers.

However, sea cucumbers in this feeding category can often be picky eaters, because some feed only on fine sand, while others prefer relatively course sand. Therefore, if the proper type of sediment a particular sea cucumber needs is not provided, it may not feed. If you have a gravel bottom in your tank or a bare glass bottom, rather than a substrate of fine “sugar” sand, do not consider sea cucumbers.

Sea cucumbers can be problematic aquarium specimens under certain circumstances because of their many unusual defense mechanisms, which may sometimes have an adverse impact on their tankmates, as described below:

(1) Evisceration or autovisceration: they may forcibly eject all of their internal organs through their anus, presumably to distract predators while the cuke makes a slow-motion getaway. This act of voluntary disembowelment surprisingly does the sea cucumber no permanent harm, as the internal organs are regenerated over a period of months, but it gives a new meaning to the phrase “puking your guts out.” Spilling their guts in this fashion is a response to a life-threatening situation — predation, chemical stress, low oxygen levels that cannot support them — and can help the sea cucumber survive until conditions are more favorable. No chemical discharge normally occurs when they eviscerate, so this odd behavior is not a threat to the aquariums inhabitants.

(2) Regurgitating Cuvierian tubules — glue traps. At the slightest provocation, some cukes expel masses of very strong, long, extremely sticky, filamentous threads (Cuvierian tubules) to deter predators. Other animals, especially spiny crabs, become hopelessly trapped in these adhesive tubules and the more they struggle, the worse they become entangled until they are as incapacitated as if they were wrapped up tightly in a straitjacket. Once trapped in this sticky web, they are doomed to a slow death. The hobbyist can intervene to save the entrapped animal(s), of course, but disentangling them by hand is a painstaking process that can be the devil’s own business.

(3) Animated Goop — morphing into tight places. Some cukes can more or less liquefy their bodies (a process that hobbyists often refer to as “goopifying”) in order to ooze or pour themselves into the tightest cracks, crevices, and hidey holes for protection. Once they’ve holed up in this manner, they inflate their bodies with water and solidify their skin again, wedging themselves tightly in place to prevent their extraction. A harmless enough trick, you might think — until the tight space they wedge themselves into and plug up is the intake, drain, or overflow of their aquarium! To prevent this sort of accident, aquariums that house Holothurians should be cucumber-proofed, a task most seahorse keepers have already accomplished in order to prevent their ponies from being suck up by filter intakes and overflows.

(4) Chemical Warfare — the dreaded “cuke nuke!” Some sea cucumbers release toxins (holothurin and holotoxin) while alive when threatened (or even after death, in some cases). These toxins can be quite deadly to fishes but don’t seem to affect most invertebrates. The group of colorful sea cucumbers known as Poison Apples are the worst offenders in that regard, and a large specimen is said to be able to release enough toxin to kill all of the fishes in a small, closed system aquarium and wipe out the entire tank. Such rare Holothurian-related aquarium accidents have become known as “cuke nukes,” an unfortunate appellation that has given all sea cucumbers a bad reputation with hobbyists.

This is regrettable because the beneficial Aspidochirotiacea burrowing and deposit-feeding sea cucumbers are such good sanitation engineers and are much less likely to find themselves in a situation where they must call their defense mechanisms into play, particularly in a seahorse tank, and far less likely to cause ANY trouble than their toxic cousins, the Poison Apples. Still, any aquarist who is considering adding sea cucumbers to his tank should be aware of the potential risks. Anyone who is contemplating cukes should read Rob Toonen’s excellent series of articles about them, which outlines the benefits and risks they may pose in greater detail. It is available online at the following URL:

Click here: Aquarium Invertebrates

Sea cucumbers aren’t for everyone, but the right kind can be useful sand shifters and detritivores for seahorse keepers that use deep live sand beds (DLSBs) or run modified reef tanks. If you want to give sea cucumbers a try, avoid the colorful filter-feeding Poison Apples, stick with the burrowing sand movers, don’t overstock (one or two cukes is usually plenty), and handle them with care. (The recommended stocking density is no more than 3 inches of sea cucumber per 20 gallons.) If you have any doubts about your ability to handle or care for sea cucumbers properly, then you will probably be better off sticking with snails (especially burrowing Nassarius snails), microhermits, and cleaner shrimp as your sanitation engineers.

So if you can obtain the beneficial Aspidochirotiacea sea cucumbers from a reliable dealer and inform him of the type of sand and grain size you have been your DLSB, they will be terrific! Otherwise, however, I would avoid sea cucumbers altogether and make absolutely sure no one tries to so you a Poison Apple.

If you use fine enough sand in your DLSB so that detritus remains on the top and cannot migrate down into the substrate, then you really don’t need any sand sifters at all other than the microfauna that come to populate any sandy substrate. I recommend sugar sized sand grains, or something finer still, for this purpose.

For additional information on setting up and maintaining your DLSB, check out the following FAQs site by the wetwebmedia guys. Skim through it carefully and it should give you lots of good ideas regarding how to proceed:

Click here: DSBFAQs

One foolproof solution to your problem would be to remove the sandbed entirely and go with a bare glass bottom on your seahorse tank. A bare bottom greatly facilitates cleaning and is much easier to keep sanitary, but it’s not very pleasing aesthetically unless/until it gets overgrown with coralline algae.

If you have sufficient live rock for adequate biological filtration, then the sandbed is largely superfluous, and you could run a bare bottom tank…

Pete Giwojna, Ocean Rider Tech Support

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