Sand Substrates - The Nitty Gritty 

(by Andy Macek with many thanks to Dentaku, Daemonfly, pyrowolf, mak, luvfishes and others who may have been inadvertently overlooked)
(December 29, 2003 / Updated March 27th, 2004)

Ok, you decided to take the plunge into sand substrates. Your reasoning may vary from the natural habitat for your cichlids to the fact that you just had to have that Tahitian Moon Sand. Maybe you just like the look, but no matter why you choose it you have to care for it. In the following segment I plan to answer most of your questions with a little help from our friends.

What kind of sand to use?

Sand used in the aquarium should be inert, meaning that it has no properties that can leach into your water. The main things you want to avoid are pesticides in the sand and chemicals used to clean the sand. Depending on your intended usage, there are sands that can increase your Ph if you want to keep African cichlids per say.

The following are noted sands that are mostly silica based and marketed by different names depending on your locale and type of store. These various sands can be purchased in any number of stores ranging from your local fish or pet store, a commercial home store (ie. Home Depot or Lowe’s) and even the pool supply stores.

Plain Silica Sand
Sarawek Sand
Creamy Silica Sand
All Purpose Sand
Sand Blasting Sand
Pool Filter Sand
Decor Sand


It is not recommended to use “play sand” or smaller than sugar sized granule sand. The potential issues here are that the lower levels become heavily compacted while the top layer is very easily kicked up. Play sand is also not always inert causing potential Ph changes and it is not consistently fully dried creating room to grow mold and parasites. There are also few specialty sands available for sale at some pet stores and online fish supply distributors. Some of these sands are specialty items that may effect your water parameters like raising the Ph or contain added nutrients for live plants. Always follow the manufacturers recommendations for use in the aquarium.

These include:
Tahitian Moon Sand
Carib-Sea African Cichlid Sand
Seachem Onyx

How do you setup your aquarium with sand?

The initial set up of your sand based aquarium is virtually the same as if you were using conventional gravel. You will start at the front of the tank with a thin covering and increasing the depth to slope towards the back of the tank. The numbers are variable depending on your experience, committed maintenance time and if you have burrowing fish. A reasonable depth at the back wall of the tank should be approximately 1 to 1 1/2 inches. Going deeper than this will require some help keeping it stirred to avoid anaerobic pocket buildup. Methods to do this are discussed later. It is not recommended to layer different size gravels with sand. In time the sand will settle toward the bottom of the tank causing the larger grained gravels to be on top. Again this is a recommendation and not a rule being that it is mostly an aesthetics issue.

How do I switch from gravel to sand?

The switch from gravels to various types to sand is a growing topic in the hobby as people are looking for a more natural setting for their fish. This process may take a little time to complete. There are two basic methods to changing your gravel, quick and not so quick. It would be recommended to remove your fish into a quarantine tank for potentially a day if you choose the quick method, otherwise you may want to use the partial change method. This does not mean a fish-in change can not be done, but one must be very careful to avoid damage to the fish.

If you choose the faster of the two methods you will need a very porous bag, such as a pair of new a heavily rinsed nylons or panty hose, to hold a portion of the old gravel for a few days. The process is fairly simple. Start by preparing the new sand by rinsing it thoroughly. Next you need to drain some water into a bucket to reduce your water level a little and give you a holding pen, remove the decorations and plants into the bucket. Carefully scoop out the old gravel into the bag you chose being sure to keep it wet. Please take extreme care if you were unable to remove your fish from the tank while you begin to add in your sand. Continue to add your sand to desired levels and then replace your decor and plants. You will now need to place the bag(s) of gravel back in the tank. Hanging them towards a side will make removing them later easier. If you are wondering why, well that is because your old gravel has established beneficial bio-bugs established on it that you do not want to lose. Placing them in a bag will allow some to transfer back into the tank. The time to complete this transfer will very from tank to tank. You will need to monitor your fish and water until the potential mini-cycle passes. If enough beneficial bio material is transferred there should be no ill effect. The more time consuming method will be safer for the fish that can’t be moved. This method is accomplished by removing only sections of old gravel at a time. As each section is cleared, new cleaned sand is put in it’s place. A good target would be between one third or a quarter of the gravel at intervals of approximately once a week therefore not removing all of the bio-bugs and giving time to recoup any that are lost. The drawback of this method would be not being able to fully remove 100% of the old gravel.

Can I have live plants in sand?

Yes. In keeping this simple, it would be beneficial to your plants to add plant spikes or root tabs into the sand. There are many types of spikes and tabs available and you should follow there recommendations for spacing etc. If you are using planted aquarium sand like Onyx, spikes would not be needed.

How do you keep it clean?

The routine maintenance of sand is not much different than that of gravel. Vacuuming is the easiest form of cleaning, but with the sand you want to hover the vacuum above the surface so as not to pull straight sand. Another method is to net the sand. This method requires a net that will allow the sand to fall back into the tank, but yet catch the detritus. Mechanical filtration can be done with any type of filter. The use of an internal or undergravel filter is not recommended. Sand will compact too tightly for a UGF to work properly and an internal filters inlet may be too low to keep from pulling sand into the impeller. Smaller tanks would benefit from small sponge filters as the suction on these is not strong enough to disrupt the sand. hang on the tank power filters or canisters work quite well in the sand tank. The inlet should be raised to approximately 3 inches above the sand. An adjustable power filter would be better as a lower flow rate will keep the output from making pockets in the sand. A canister filter is my choice as you get a higher filter capacity at a lower flow rate and input/outputs are easily modified.

The addition of a sponge over the input is also highly recommended. This prefilter will reduce the amount of particulate that can damage an impeller. No matter what filter you choose, pick up a spare impeller. The cost will be greatly out weighed by having it close when you need it.

Are you worried about those anaerobic gas pockets?

A major concern for the aquarium with sand as the substrate is anaerobic gas pockets. The combination of the fine grains of sand and the depth of your substrate can lead to these pockets that are actually hydrogen sulfide. Hydrogen Sulfide, often seen as H2S, is toxic to you (large amounts) and to your fish! There are several ways to help combat this potential problem. The first would be, as with gravel, don’t go to deep. A very fine gravel should not be more than 3 cm deep and allowing more depth as the grain size increases. As a fish keeper you can help prevent these pockets when you do your routine maintenance by simply stirring the sand with a finger or other similar aquascaping tool.

Here's a great link that talks about H2S including Steve Hampton and Tom Barr:
http://www.plantgeek.net/forum/viewtopic.php?t=1424

Would you like your sand grazer or vacuum to be of the living sort?

Many of the previous topics can also be supplemented with live creatures. Snails, shrimp and many types of fish can help out the cleaning side. Malaysian Trumpet Snails will gladly clean waste laying on your sand and have the added benefit of being a burrowing snail by night that will till your sand helping to eliminate gas pockets. The draw back to these snails is that they can overrun a tank with their live bearing reproduction, although a few snail eating fish from the Botia family (loaches) will gladly help keep the numbers down. Many shrimp, including Ghost shrimp, will consume detritus off the sand as well. Both the snails and shrimp have various pros and cons. Ghost shrimp will not over populate your tank. Baby shrimp require micro and suspended algae to live and without copious amounts of cover, they will be food for other fish and adult shrimp. Ghost shrimp will also help the natural balance of life by eating fish eggs and weak fry.

They are also many fish that can be used as sand tillers and trash compactors. Many of the Corydoras and Botia (loaches, i.e.: Horsefaced and Kuhli) species in a small shoal will keep your leftovers cleaned up. They are also known to play and burrow in the sand helping out with gas pockets. Others that are a little harder to find are Giraffe Catfish and the Hoplo cat. The list of fish that will feel at home in the sand is endless as many are from sand based lakes and rivers. Many types of fish, including cichlids, will sift the upper layer of sand for food helping to keep it clean.

 

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