Adding sand

If my tank is full with water and starting to cycle should I just add the sand while the water is in the tank, or would it be best to just drain it and then add the sand, water, ext. ?

I just decided that i should add some sand below my river rock. lol

Thank you

Yeahhh, just add the sand in now. Make sure you rinse, rinse, rinse the sand. When you think you've rinsed it enough, rinse it twice more!

What's the river rock like?

I shudder whenever I see someone mention adding sand to their tank. I still don't think my arms forgiven me for what I put it through last time!

I also second the curiousity of said river rock!

Well I havnt gotten my axolotl yet. I'm trying to make everything perfect first. All the reviews about river rock say its so hard to clean but I'm going to try it out, I don't think it could be much harder. I just love the rock look. But I decided to to a tin layer of sand and then river rock on top, to give it a natural feel. But havnt decided if I will do light or dark sand, because I plan on getting a wild and luistic.

I'm sure ill be complaining about my arms after tonight lol.

Durbimac000 said:

Well I havnt gotten my axolotl yet. I'm trying to make everything perfect first. All the reviews about river rock say its so hard to clean but I'm going to try it out, I don't think it could be much harder. I just love the rock look. But I decided to to a tin layer of sand and then river rock on top, to give it a natural feel. But havnt decided if I will do light or dark sand, because I plan on getting a wild and luistic.

I'm sure ill be complaining about my arms after tonight lol.

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Lol, you sure get a work out!

Do be careful with the rocks. They need to be bigger than your axolotls head will ever be, so if you get a juvie and he grows up, the rocks are still bigger. Otherwise the chance you will end up with a sick or dead axolotl is quite high

The rock look does look pretty funky, unless it starts to get grubby and nasty. Have you considered some piles of rocks? You could add some nice plants in between them... Oooh, stop me before I head out to the aquarium store AGAIN!

Unless you plan to bust the seams on your tank. Never put sand or gravel in a tank with water in it. It is best to landscape your tank first and then add water, that way if there is a problem you do'nt have that much water to drain, or heaven forbid cleanup.

areynoldssr said:

Unless you plan to bust the seams on your tank. Never put sand or gravel in a tank with water in it. It is best to landscape your tank first and then add water, that way if there is a problem you do'nt have that much water to drain, or heaven forbid cleanup.

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Can you give us more information here, Snake? Thats a pretty bold statement against adding sand afterwards!

I've done it both ways and not had an issue, but perhaps I was just lucky.

Can you explain why this is the case, for future visitors who may hit this page?

As you know sand is dense, the seals on a tank can be busted from the pressure caused by sand displacing the water. Water is pushed outwards and up the seals can only hold so much pressure before they split. Try cleaning about seventy gals of water from the floor and ruining a 210 gal tank. Aquarium 101 you never move one with water or large amounts of sand or gravel in them. You weaken the seals. (forty-five years of raising fish) if you do add material after filling a tank you should drain at least 3/4ths of the water and still run the chance of weaking your bottom seals. You have been very lucky.

areynoldssr said:

As you know sand is dense, the seals on a tank can be busted from the pressure caused by sand displacing the water. Water is pushed outwards and up the seals can only hold so much pressure before they split. Try cleaning about seventy gals of water from the floor and ruining a 210 gal tank. Aquarium 101 you never move one with water or large amounts of sand or gravel in them. You weaken the seals. (forty-five years of raising fish) if you do add material after filling a tank you should drain at least 3/4ths of the water and still run the chance of weaking your bottom seals. You have been very lucky.

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Ooh 'm so glad you posted this! Planning on getting new sand soon (ish) but my tank is already filled and has my monsters living in there, I was just going to put the sand in with the water and knowing my luck, the tank would have gone boom!

Im quite curious as to your reasoning there Snake .

First off, if you place a certain volume of sand into the tank, it only displaces that volume of water. That in itself doesnt change the pressure, but rather the added sand contributes to the pressure change.

The pressure at the bottom is calculated with the water pillar and when you add sand, add the "sand pillar". However, the tank should be designed with this in mind, and the rise in pressure from the sand shouldnt be able to break the sealing in the bottom, or else it would break not only when you put the sand in, but by just having a substrate in the tank at all?

Pressure=DensityOfSand*GravityConstant*HeightOfSand+DensityOfWater*GravityConstant*HeightOfWater

The end pressure should be the same, regardless whether you add the sand or the water first.

In any aquarium you must only use a thin layer of sand, or you can risk gas bubbles forming underneath, and these gasses can be dangerous to aquatic life.

Sand is also heavy, and I guess it could pose a risk having too much in there, as you're adding more weight than you would using gravel I believe. But it's standard that most new aquaria come with a thick piece of foam to cushion the base to evenly distribute that pressure to prevent cracking. It would also have a lot to do with the design of the tank, a tank with more joints ie a standard rectangular tank would have a bigger risk of popping a seal or even a panel than one that has a curved front and sides or a "bow" front tank.

My axie tank is great in my opinion, the front and sides are all one piece, with nicely curved corners so I think it's better on the animal to have those gradual corners, and it seems to let my axie follow the sides of the tank more naturally, as she likes to wander about the edges.

A quick example of my reasoning.

A tank with water at the height of 0.4m has a bottom pressure of:

Pwater=0.4m*9.81*1000kg/m3=3928Pa=3.9KPa
Note that this is the gage pressure, that is pressure over the atmospheric pressure.

If you add 5cm of sand you add this pressure:

Psand=0.05*9.81*2500kg/m3=1227.5Pa=1.2KPa
Again this is the gage pressure and the density of sand I found by googling, and from what I was able to gather quickly, this is quite heavy sand.

The total gage pressure in the tank should be:

Ptot=Pwater+Psand=3.9KPa+1.2Kpa = 5.1KPa
This regardless in what order your add the two "materials" in.

So unless you dump everything in at the same time somehow and the sudden pressure change weakens the seals, it should not matter in what order you put sand and water in. Just take little at a time and the pressure change is minimal over time. The final pressure stays the same .

cml said:

A quick example of my reasoning.

A tank with water at the height of 0.4m has a bottom pressure of:

Pwater=0.4m*9.81*1000kg/m3=3928Pa=3.9KPa
Note that this is the gage pressure, that is pressure over the atmospheric pressure.

If you add 5cm of sand you add this pressure:

Psand=0.05*9.81*2500kg/m3=1227.5Pa=1.2KPa
Again this is the gage pressure and the density of sand I found by googling, and from what I was able to gather quickly, this is quite heavy sand.

The total gage pressure in the tank should be:

Ptot=Pwater+Psand=3.9KPa+1.2Kpa = 5.1KPa
This regardless in what order your add the two "materials" in.

So unless you dump everything in at the same time somehow and the sudden pressure change weakens the seals, it should not matter in what order you put sand and water in. Just take little at a time and the pressure change is minimal over time. The final pressure stays the same .

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So in theory, if I did it the way I planned to, which is add a cup or two at a time only reaching around 1 inch tops in depth it should be fine? Got a 4ft long rectangular tank with polystyrene under, I don't fancy the task of emptying all the water a second time in as many weeks but just as much don't fancy my tank going boom!

To CML- Thank you for your math equation, it deffinately helped me understand the displacement. & we've all got to love google. lol

Thank you to everyone for your thoughts and suggestions, I am planning on going and picking the sand up here in a few minutes, add it to my tank tonight along with some plants.

I have to say that I have over 30 years of aquarium experience and have never had a problem adding rocks or sand with water in the tank. Actually, in most cases, I find it easier to add substrate with water in as gravity can be the enemy too. Thank you CML for the equation, greatly appreciated.

You have to use a bit of common sense when working with a water filled tank, this is true. For example, if you plan on adding 50 lbs of substrate to a tank, you can't simply dump it all in at one time. I add my desired amount a little at a time and certainly not from a great distance above the tank either. I submerge my container until it is just a few inches from the bottom and add slowly so I don't stress the seams or the bottom pane itself. If adding large rocks, you have to use even more care. When I added these, I painstakingly placed each one on the bottom by hand.

@Mac, I tried the big rocks, yes, they look great. However, I don't care how thorough I thought I was cleaning it, the gunk I found while removing it was alarming. Decaying bloodworms, parts of nightcrawlers, pellet debris, and other unmentionables were found. You may want to make sure your gaps are filled with sand to avoid this issue. Not to mention I'd love to see your set up when you're done!

Just glad I could help out ^^.

So in theory, if I did it the way I planned to, which is add a cup or two at a time only reaching around 1 inch tops in depth it should be fine? Got a 4ft long rectangular tank with polystyrene under, I don't fancy the task of emptying all the water a second time in as many weeks but just as much don't fancy my tank going boom!

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You should be fine yes =).

As Shannon said, just use common sense and everything should be okay!