Which goes in first? Rock or Sand?

[litebrite]

I set up my tank with a 4" sand bed. Added lots of rock and filled it. Before I add fish, I was thinking what if a little fishy digs a hole under a rock and the whole pile tips over and breaks the side glass. Should I take out the rock and sand, then put the rock directly on the bottom to prevent digging?

Tank 30" tall. Rock is piled 18 inches tall. Or is it very unlikely a fish will dig a deep enough hole under a rock to tumble the whole pile? The rocks are solid but if the base shifts some of the rocks can roll off the top.

[pat8you]

If you end up getting like a sand sifting goby or a similar burrowing fish they can dig out quite a bit under the rocks. It is usually recommend that you try and get your rocks on the bottom or at least close. Regardless, better safe then sorry i would think.

[tamra&steven]

if you are worried about somthing moving your rock work around then you should move some sand out of the way and set your rocks down closer to the bottom of the tank. i set a thin layer of sand in the tank first then the rocks then the rest of my sand. beacuse like said before gobies will get under your rocks and they will fall.

[litebrite]

Thank you. I'll pump the water out and put the rock directly on the eggcrate sitting on the glass, then put the sand around the rocks. Thanks.

[litebrite]

Done, big job. I emptied the 150 gallon completely, water, rock and sand to get to the bottom. 8 hours later... The rocks are now sitting on the eggcrate directly over the glass bottom. Then after the bottom layer of rocks were in place I added 4 inches of sand around. It is so solid now I was able to make caves by stacking the rocks further apart since they are more solid. Looks great and I will sleep at night now. I'm ready for the strongest digging goby.

[MommaFishels]

I have a Orange Diamond Watchman Goby, he is too funny. He digs all the time. It is amazing to watch the size of rocks he can pick up. He hasn't tipped any rocks over yet!

[CatatonicBug]

Originally Posted by litebrite

Done, big job. I emptied the 150 gallon completely, water, rock and sand to get to the bottom. 8 hours later... The rocks are now sitting on the eggcrate directly over the glass bottom. Then after the bottom layer of rocks were in place I added 4 inches of sand around. It is so solid now I was able to make caves by stacking the rocks further apart since they are more solid. Looks great and I will sleep at night now. I'm ready for the strongest digging goby.

Don't forget to post some pictures of the construction! We all enjoy seeing the projects as they come together.

[litebrite]

Thanks for all the advice. It's a bit disappointing that my bottom cave area is burried under 4 inchs of sand. I am considering taking out 2 inches of sand to open up the bottom cave area. When I put the rock in directly on the bottom you could put your fist from front to back with the caves. Now they are completely filled in with sand.

Pros and Cons. Can I remove 2" of sand or do I really want it for bio reasons? How much more benefit will those etra 2 inches be? Some areas have 6" of sand too.

Thanks

[pat8you]

The way i understand it the only time you see a substantial benefit from a deep sand bed is when it is left undisturbed (no burrowing creatures) and bacterial can build up there that consumes nitrates. Some critters like a pistol shrimp will need a deeper sand bed so if you want to keep something like that then you would need to keep the 4-6". If not then its my experience that a goby does just fin with two inches (he will move the sand how he wants it) and the more sand bed you have the more you have to keep it clean. Someone please correct me if i'm wrong. haven't been in SW for that long. Some of the experts will know more.

[litebrite]

So glad I took out took out the rocks and replaced them directly on the bottom in the 150 gal tank. My other tank with a 4" sand bed also had a pile of rocks but much lower. I have a large damsel that digs holes all around the tank and tumbled over a pile of rocks against the glass. The fish moved so much sand that it looks like a valcano and a hole in the center with the bare glass showing. Had this been my large tank with big rocks it would have been a situation... Definitely put rocks on the bottom and sand around the rock not floating rock over the sand if you plan on making a very tall pile.

THANKS FOR THE ADVICE!!!! IT WAS GREAT ADVICE.