# how to change substrate in an established tank



## rininger85 (Jun 30, 2013)

are you currently running a filter with floss in it? When I first attempted to switch from gravel to eco-complete on my first tank I was running a filter with only a bio-wheel in it. I hadn't really done my research and it ended up causing my tank to crash and kill everything. I was told many times on here that the reason was because I hadn't ran the filter floss, if you run filter floss it should have enough bacteria in it to maintain your tank when you change the substrate is what I was told (assuming its been in there for a while...)

The safe route is the 25% approach... if I were going to do that I'd cut a piece of acrylic / lexan and divide the tank off in to the different areas to keep the gravel and eco-complete from mixing if you are looking to go all eco-complete.

Personally I'd suggest against going 100% eco-complete. I really liked the look if it, but couldn't get plants to grow in it. You need something else with the eco-complete, so do some reading before you make the move. I personally got on board the miracle grow potting soil wagon, my 10 gallon work tank is miracle grow capped with gravel capped with Tahitian moon sand and it has grown really well. My 40B tank at home that I'm currently breaking down I started out with miracle grow capped with eco-complete, but I cracked the tank while setting it up so then my eco-complete and miracle grow got mixed together when I replaced the tank and I ended up capping that mixture with fluorite... my plants have grown, but not as well as the miracle grow / gravel / sand mixture...

maybe a eco-complete / sand mixture would work well... I really like the Tahitian moon sand look, although it eventually migrated to the bottom of the substrate.


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## Diana (Jan 14, 2010)

Skim the top layer of gravel, just about 1-2 rocks deep. 
Put that much into several mesh bags. Hang these in the tank where there is good water flow. 
About once a week, remove one. 
If you bury the gravel with the bacteria on it then the low water flow is not going to bring the ammonia to the bacteria, and the bacteria probably won't be of much benefit. Keep the bacteria exposed to the water flow. 

Keep the filter and any decor, and (of course) the plants.

Alternate: If you want to change more things then you could get a bottle of bacteria that includes Nitrospira species of bacteria. These are the actual species of bacteria that you are trying to save when you do a major overhaul.


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## xxoczukxx (Aug 16, 2014)

Erm i am currently running two filters, one with a tetra bio bag (an HOB) and a sponge filter. i was thinking about doing another type of substrate with the eco but i really dont like the idea of sand because i know it will simply fall to the bottom eventually. i heard a lot of success stories of eco complete only with root tabs and ferts and stuff growing well with dhg (what i plan to do) although the initial rooting was difficult. 


If thats the easiest way to go (mesh bags with gravel) i will do that when i get the chance. I maybe also leave some gravel under the eco so i can form a nice hilly aquascape


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## Diana (Jan 14, 2010)

The EC I got was pretty close to sand in texture, only a little bit coarser. I think it would fall through the gravel. From quite a few posts here, it seems like the EC is coarser than that. Maybe I got a really fine run of the material that is atypical.


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## jrill (Nov 20, 2013)

Diana said:


> The EC I got was pretty close to sand in texture, only a little bit coarser. I think it would fall through the gravel. From quite a few posts here, it seems like the EC is coarser than that. Maybe I got a really fine run of the material that is atypical.


Eco complete comes in both coarse and fine, although the fine is harder to find.


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## Diana (Jan 14, 2010)

Ahhh, I guess I got the fine, then. A lot like sand, but I remember a couple of larger pieces. Not more than half a dozen in the several bags I bought, and they were perhaps 1/2" (It has been a long time since I dug into that tank).


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## talontsiawd (Oct 19, 2008)

I have been successful with this method but it requires you have more than one tank, or spend money on plants you don't need. First, add a bunch of plants, they can float, no need for them in the substrate. Let them stay for a few days, accumulating BB. Then siphon out the old substrate. Replace with new. Pull the plants. 

That fights the cycling battle in two ways. First, the plants take up the excessive ammonia, etc, second, they accumulate BB. Now, this needs a healthy filter and, if you have two tanks, you may be better off swapping some fish to lower the biomass. 

In general, I relocate fish when possible when redoing any tank but if I can't, that has worked for me. I am not the best fish keeper either. 

I would do water changes more frequently, however you plan to do it.


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