Simply because I could find nothing about it when I was looking, I'm making this how-to thread on removing dirt from a tank. This method will ONLY work if you've capped the dirt with gravel, I can't think of any method to separate sand from dirt. This method will empty the tank to bare glass. You will loose some gravel with this process.
Overall, it took about 4 hours to clean out the tank, clean the gravel, and rescape my 5 gallon tank. Your time may vary, and this would be more difficult for larger tanks.
Why would you want to remove dirt from a dirted tank?
-more freedom with scaping
-pH issues from soil leeching
-any reason you want really
Here's the basic steps summed up. I go into greater detail later on
- Remove looser pieces of wood, plants, and decor that needs to be kept wet. Put them in a container large enough for all that, and your fish and shrimp as well.
- If you haven't already, fill said container with water and move over filter, if it is a submerged or HOB filter. Otherwise, make sure there's filtration on the container
- Move over fish/shrimp to container.
- Make sure everything you want to stay wet is in the container, and set where it won't be disturbed
- Remove rocks, substrate supports, and any additional decor that can be dried out. Leave only the substrate.
- Drain out water, and move ALL substrate into a container/s that the substrate can be washed in
- Clean out the tank, removing remaining dirt, algae, ect.
- Add enough water to cover the gravel, and scrub the gravel against itself, like washing rice.
- When you feel the water is as dirty as it can get, drain the water, refill the container, and scrub again
- Repeat the scrub/drain procedure aprox. 10-25 times, depending how clean you want your gravel.
- To add the gravel back to the tank, put it in a smaller container, add just enough water to cover, and gently shake the container for 10 seconds to separate gravel from grit. Then scoop up gravel and add to tank, being careful to not add the grit.
- Rescape, and return fish and shrimp to tank
In my case, I was having compaction issues and really wanted a bit more freedom when it came to scaping. I'd had the rocks in this scape in their positions since I first set up the tank, about 2 years. I wasn't able to move the rocks because they were marking the borders of where I'd used the dirt, and would have caused a huge mess to try and move. So I decided it was time to try to remove the dirt.
I started off by filling the fish container, moving over the wood pieces and filter. Then came time to try and catch the fish. This would have been significantly easier with colorful fish, rather than well-camouflaged wonders I have (Heterandria Formosa). I also have red rili shrimp, a version of the red cherry, these were difficult to catch as well. Once all those were settled and not going to be disturbed, I moved onto the tank itself.
Fish in their temporary home:
After this I removed the plants, and put them in a container in the fish bucket so they wouldn't get dried out. I pulled out the rocks and let them in a bucket, and started removing the gravel and dirt. There were several clumps of dirt that I just pulled out and tossed. My main goal here was to get everything out of the tank. After that I moved tank, gravel, and a bucket of water outside where it wouldn't matter if I made a mess. A hose would have been a more convenient water source, but I don't have external water in my backyard.
I cleaned out the tank first, getting out all the dirt and stains. Deeply considered de-rimming the tank, but then realized that the parental unit who had bought me the tank with the rule "Don't do anything weird to the tank" would likely be unhappy with me. I would have loved to de-rim the tank, especially with the scape I went with, but what's done is done.
Then came the gravel scrubbing. Pretty simple, just tedious and takes awhile. Good way to water the yard though. I didn't see the water clearing up until around the 7th scrubbing, but I wouldn't really call it clean enough to use until at least the 10th round, and even then, it would have only been in a non-display tank. I kept going until the 20-21st scrubbing. It still had quite a bit of grit in the gravel though. A trick I did figure out was to drain out the water very quickly after scrubbing, since the dirt will settle quickly.
The remaining grit:
Overall look after 20 scrubs:
This was about as clean as I was willing to make the gravel from scrubbing alone. I started adding gravel back to the tank by scooping up some gravel into a smaller container, adding a small amount of water, and gentle shaking the container until the grit separated and settled at the bottom. It was fairly easy to scoop out just the gravel, but I did get some grit in the tank. Not enough to make a difference, in my estimation. You can also do the same process in the larger container, but I found it harder to avoid scooping the grit with the gravel. This is one of the places where I ended up throwing out some of my gravel. It was too difficult to separate it from the remaining grit without using a screen separator.
Grit in the small container:
In the larger:
After this was rescaping, adding water, and reintroducing the livestock. Overall, not as difficult as I expected and I'm very happy with the results. There's minimal clouding in the tank, though it's been a few hours, but I'm certain that that will settle out.
Closeup of gravel in the filled tank:
The finished rescape, 4 hours after filling: