Tropical Fish Keeping - Aquarium fish care and resources

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Tyyrlym 01-22-2009 11:11 AM

Sand Substrates
Using sand for your substrate is a popular option in the hobby. There is precious little information on exactly how to do it however. Gravel has long been the standard aquarium substrate and most official sources have information on using gravel but make no mention of sand. This leaves people with a lot of questions. Hopefully I can answer some of them.

First, what are the benefits of using a sand substrate?
  • It looks great. Ok, that's mostly my opinion but it is something that you don't see every day.
  • Sand substrates are easier on bottom feeders. Some bottom feeders, such as cory catfish, have delicate barbels. Even smooth gravel can cause damage to these delicate structures. A sandy substrate is easier on them.
  • Detritus lays out on top of the sand, making it easier to spot and clean. This reduces the amount of gunk decaying in the aquarium pumping nitrogenous substances into the water.
  • It's cheap. A 50lb bag of play sand costs about $4 at my local Home Depot. One bag will handle anything up to around 40 gallons. Two will handle anything up to around 75 or 90 gallons. Eight bucks will buy you about five pounds of aquarium gravel.
  • White play sand is a good reflector, a white sandy substrate ca brighten up an aquarium.

What are the drawbacks?
  • Detritus lays out on top of the sand. You can see it easily. Not a huge deal if you keep up on your vacuuming but stuff gravel would hide sand will make obvious.
  • Vacuuming is a bit more difficult.
  • Can cloud water if disturbed.

Most of the drawbacks of sand can easily be handled with proper maintenance and technique.

Types of Sand to Use:
Play Sand
Pool Filter Sand
Silica Sand

Do Not Use:
Aragonite Sand
Beach Sand
Crushed Coral
Any sand labeled as for use in marine aquariums


How do you add a sand substrate to your aquarium either new or existing? No matter how you're doing it there is one common step. Rinse it. That bag of play sand sitting there isn't homogeneous. There's assorted bits of stuff in it that isn't sand, sticks, leaves, things you'd probably not think about. Even the sand grains are different. Some are large and coarse, some are just powder. The goal of rinsing is to remove everything but the big coarse grains, or as close to it as possible.

What you'll need:
Bucket - I use a five gallon. Directions will be based off a bucket this size.
Hose - Preferably one with a spray handle that lets you turn it on and off.

1) Pour sand into the bucket. I add about 10 to 12 pounds of it to my five gallon.
2) Add water. I aim to have about four inches of water over top of the sand.
3) Agitate. If you've got the sprayer for the hose this will help. I turn mine on stream and let it pound into the sand, it stirs it up. If you don't have this just reach in and start churning the sand with your hand. You'll know you're doing good when you stop feeling piles of sand and it just feels like water. All the sand is now in suspension.
4) Wait. You need to give the heavier particles time to settle out of the water. Too little time and you'll pour out good sand and bad. You don't want to give it too much time though as the fine stuff will start to settle out and then the rinsing isn't as effective. I usually give it about five seconds and start to pour things out. It's important that you monitor things closely and use your own judgment on this part.
5) Pour. Slowly pour out the excess water. It'll be milky and brown at the start and this is good. Don't pour too fast, you'll sweep off the upper layers of good sand along with the water.
6) Repeat.

At first your water will look like chocolate milk. Brown and murky. As you go though the water will start to clear. Less gunk will remain suspended. You want to keep rinsing the sand until the water is clear and further rinsing isn't improving things. I average about 15 to 25 cycles of rinsing for each bucket. It's a lot but it pays off in the end. Well rinsed sand clouds very little when bothered. I can move plants, decorations, stir the sand, etc. and my water does not cloud. My sand was rinsed well enough to leave mainly only large particles that sink rapidly, little of the small powdery grains left to float around. Extra rinsing up front results in less clouding later. If in doubt, rinse it again.

Now you've got rinsed sand. If you're adding it to a new aquarium you want to add it first like any substrate. Just scoop it out of the bucket and dump it in. Don't worry, it looks like crap, just dump it in. Once all your sand is in add some water, enough to cover the sand. This smooths it out and with a little work from you it should redistribute nicely. Looks better now doesn't it? Now decorate and add water as normal. Your water will cloud, this is unavoidable no matter how much you rinse. You have two options, the first is to just wait for things to settle out, this can take a while. The second is to run a filter and let it clear things out. So long as you don't run the filter as you're adding the sand what is suspended in the water is stuff small enough that it shouldn't cause damage to your filter. Be aware that your mechanical filter sponge/pads will clog quickly so keep an eye on them during this and expect to change them out. With a filter running your tank should clear in less than 24 hours.

If you're adding the sand to an existing tank, such as a change out from gravel to sand, the procedure is a little more involved. Note, if you use an undergravel filtration system you cannot use sand. You'll need to change to another method of filtration before you can do the replacement. Make sure your tank is filtered and cycled. I recommend doing this all at once, not a little at a time. I also recommend, STRONGLY, removing the fish if at all possible. I'd move the filter, fish, and heater to a bucket or QT tank for the duration of the change. If that's not possible, well they're not going to be happy but you can't do anything about that.

1) Siphon out as much of the water as you can, I'd leave only a few inches in the bottom. This makes it easier to work.
2) Remove all decorations and plants. Move them to a bucket full of tank water is best. Take whatever precautions are needed with the plants.
3) Remove the gravel.
4) Vacuum. Add more water if you have to but clean up the bottom of the tank as best you can. You do not want to leave any detritus on the bottom to be covered by the sand.
5) Add rinsed sand.
6) Rebuild the decor.
7) Fill with water. Dechlorinated and at the appropriate temperature.
8) Put the filter back and start it up.
9) Re-introduce your fish. You can do this right away if you want or wait for the water to clear in a day or so. If you wait then keep your filter with your fish.

It's not a bad idea to collect some of the outgoing gravel (swished liberally in old tank water) and put it in a mesh bag or pair of panty hose and place it in the tank in a high flow area. It is also my opinion that the best way to do this is all at once, instead of a little at a time. Doing it all at once gives you the best ability to start fresh with the substrate. Moving in a bit at a time will trap a good bit of crud in the sand that you might otherwise have gotten out if you did it all at once. I also believe it is less stressful on the fish to do it all at once rather than a little at a time.


Now that you've got a sand substrate how do you maintain it? First off, nothing much has changed, you're still going to have to vacuum and the same one you used on gravel you'll use on sand. The only real difference is that rather than jamming it into the sand like you would with gravel, you want to hover the siphon over the top of it. Swirl the siphon to help nudge things off the bottom and pick them up. You want to get the siphon as close as you can without picking up sand. It'll take a while but you'll get it. I still pick up some sand from time to time while vacuuming. Don't worry about it.

Stirring the sand. Let me add the disclaimer that I am including this because its a commonly accepted practice and isn't going to harm anything. Personally I am of the opinion that it is unnecessary. After vacuuming the sand, you don't want to bury any detritus better to vacuum it up, you stir it. I used a two pronged kitchen fork for a time. Just something to move the sand about a bit and release any pockets of gas that might be building in it. Do this during the weekly maintenance routine.


There's everything I know. If you have any questions just ask.

JohnnyD44 01-22-2009 11:34 AM

wow!!!!! what a great post!!! thanks so much!!!!

if i move my fish to a 5 gallon bucket for the time being while I change out the gravel to sand.....with an air stone, do you think they will be ok until I get the sand in and get the tank replanted? I don't have an extra tank laying around so they would go in aquarium water with no filter for a little while. I would of course unplug the filter before training the tank.

again, what a great post!!!

1077 01-22-2009 11:48 AM

Very informative,, nice job TY.

iamntbatman 01-22-2009 12:06 PM

Great post!

Some extra stuff I thought of:

If you're adding sand to a tank full of water, you can do it fairly easily. After you rinse the sand in the bucket, leave enough water in the bucket to cover the sand plus an inch or two. Add some water conditioner and mix the contents of the bucket around. Then, take a juice glass or any similar sized container and scoop out some of the sand with water on top. Gently lower this into the tank, all the way to the bottom, and gently pour out the sand. Having a sand/water mix in the bucket is best because if you have only the wet sand, as you lower your glass into the tank water will pour into the glass and disturb the sand and you'll make a mess.

I've never done this on an established tank, but I'm sure it would work fine. Of course, you'd want to do this slowly (as in a third of your floor space per week) so as not to upset your biological filter too much.

Kim 01-22-2009 08:04 PM

I'll bump this up because it is so informative! Great job ;) It should be made into a sticky...

iamntbatman: I did this method with my 29 gallon. There were no fish, but it was full. I rinsed it off well enough that it didn't cloud the water too bad and it settled even without a filter pretty fast.

Twistersmom 01-22-2009 08:49 PM

Good job!!! very nice post!

Tyyrlym 01-23-2009 07:27 AM


Originally Posted by JohnnyD44 (Post 165778)
wow!!!!! what a great post!!! thanks so much!!!!

if i move my fish to a 5 gallon bucket for the time being while I change out the gravel to sand.....with an air stone, do you think they will be ok until I get the sand in and get the tank replanted? I don't have an extra tank laying around so they would go in aquarium water with no filter for a little while. I would of course unplug the filter before training the tank.

again, what a great post!!!

You should be able to set the filter up to work in the bucket. If not I wouldn't leave the fish in the bucket for very long. An hour or two at most. In other words have your sand rinsed and ready to go and no one banging your door down needing you to do something. If you don't run the filter then you need to ensure that the media stays moist. If it doesn't the bacteria will die out and you get to recycle the tank.

FishFreak95 08-29-2009 09:07 PM

Someone should sticky this

MoneyMitch 08-29-2009 10:34 PM

sticky written all over this great info that i will employ myself when i get that far

hulu 10-20-2009 08:35 AM

This is great! Awesome info regarding sand substrate! I'll be sure to follow these procedures when I convert from gravel to sand :-D

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