Best way to change substrate in a tank?

[pcole6765]

I have this really ugly blue gravel in my tank and I want to switch it out. What is the best way to do this with out causing much stress to the fish? I know there's some biological junk in there that needs to stay so how do I go about changing the gravel without messing with that too much either?

[fischkopp]

Take the fish out, put them in another tank or a (clean for aquarium use only) bucket. Don't worry about the biojunk, it will come back soon enough. You should be fine as long as you keep your filter untouched.

[pcole6765]

Awesome..thanks

[Fishnut]

Just in case you loose a lot of "bio junk" aka beneficial bacteria, feed minimally for a couple of weeks and test your water to make sure it's stable.  I say feed minimally because if there's a deficiency in the beneficial bacteria, the less food you feed means the less poop the fish will produce, which is less strain on the remaining bacteria.

[Agnate]

The BEST way to do it without causing stress to your fish is to take the top layer of rocks from your current substrate and put them into a mesh bag (one of the media bags you can get from a LFS).  Then, put that bag of substrate into the new tank when you move the fish into it.  It's more effective near the filter output, but leaving it on the substrate is fine as long as there's some water circulation in the tank.  Leave it there for about 2-3 weeks and then you can remove it.  If you find it ugly, just throw some moss in front of it for the time being. 

Do this in addition to maintaining the bacterial culture in your filter's media.

[dan2x38]

pantyhose/i] this is what I did in the past but I used pantyhoses much cheaper same affect.

I drained 50%-60% of the water into buckets & bowls anything clean but no cleaners or soaps... I stored the fish in one of the buckets and plants in another. Drain remaining water down the drain. Scoop a bunch of gravel into pantyhose and keep wet in a bucket. All filter media keep in tank water bucket even adding an airstone will help to keep as much bio-bacteria alive and well.

Now scoop out remaining gravel. Don't remove the last couple inches of scummy water it is full of bio-bacteria. Now I slowly lower the new substrate into the tank scoop at a time. I aim for 3" of gravel even a little more won't hurt at all. If you have not done so at this time level your tank and add some Styrofoam under the tank skirt.

OK place a plate on top of the substrate and slowly pour in the old water from your buckets. When it is half full do your aquascaping and planting too. Now finish adding the old water. Now top off with clean treated water match temp. Add the water slowly so least amount of air bubbles are formed.

Get your filter/s started back up & heater/s. Put all the media back in. Like Agnate suggested add the bags of old substrate under the filter/s output/s. Now add your fish back in.

This is how I did it. Took me about 5 hours. I fixed my background and did some other maintenance. I was glad I did it by total shut down was so easy. By the next morning the dust and dirt had settled. Give it a day or two then rinse your filter/s in a some used tank water. Also have to dust off your plants and decorations a couple times.

Have fun... it's like setting up a new tank...

[Adam]

Take your fish, about 50% of the water and put them in buckets.  Don't clean your filters.  Then take a fish net, and scoop out as much as you can.  I then take the tank, and scrub it with a brush/sponge/something outside or in a sink to make it completely clean.  Then put some water back in, then put substrate (not substrate first as it will hold air bubbles), then your water and fish.