# Replace or add Eco Complete to existing gravel?



## onedollarinmywallet (Sep 24, 2013)

I would like to transition my current tank (20G) which currently has a mixed of plastic plants and some live plants to an all-live plants setup that is low tech based. My current substrate is gravel (see attached photo of what it looks like) but I have bought two bags of Eco-Complete. Lighting is a Finnex FugeRAY that I just recently purchased. 

What would be the best and least disruptive strategy or approach to either replacing or adding EC to my existing gravel? I'm thinking there are two options here: either replace the existing gravel completely with EC or just add or EC on top of the existing gravel.

The process that I would take would be:

1. Drain a bucket full of existing aquarium water and add a heater and air stone, and net out all the fishes for the time being.

2. Remove all the current decorations (driftwood, plants, etc.)

3. Drain at least 50% of the existing water into buckets.

REPLACE:

Drain all water, and remove existing gravel completely and then replace with EC.... or

ADD TO EXISTING:

Drain all water, and add EC on top of existing gravel

4. Plant new live plants, add back decorations (wood, etc.)

5. Add back existing water as well as new prepared water.

6. Add back fishes.


Also, the bag on the EC said that if I were to add to existing substrate, I should discard the "black water" in the bag? Is that true? What if I were to replace my gravel completely with EC? Would I use the black water in the bag?

Thoughts?

Thanks!


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## andrewq (May 22, 2013)

Most of the beneficial bacteria is in the filter media. I would remove existing substrate, and put it in a panty hose or some type of mesh. Then put new eco complete, and put old subtrate while in mesh bag on top of EC. Might not look pretty but I will help the gravel get established.


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## Nestle_ (Jul 4, 2013)

pull everything out down to the old substrate. if you're going to make any hills or higher areas, do as was suggested before. place the old substrate into bags like pantyhose or mesh bags, BUT place it under the new eco complete. the bags will keep it down and not allow it to mix, while doing double duty, holding up a hill and seeding the new substrate.
just dump the eco complete right in, and if you're new/fresh water looks gross to you then do a 100% water change. depending on how dirty your old gravel is, you may want to do this anyways. 
leave the water level low when you plant, just makes things easy. put the wood in first, and keep it wet while you're rescaping so you dont have issues with floating wood as you refill the water.

once everything is back in place, let your filter run for an hour or two before you put the fish back. just because the shift of the old substrate will put a huge amount of bad stuff into the water, and can cause a huge fish kill off even 2 weeks down the road....


the best plan for this tear down, is to get another tank, doesnt need to be same size, just big enough to hold the fish, and get a sponge filter cycling in the old tank for a week or two.
once you get your plants, fill up the holding tank, put the sponge filter over there, let it run for an hour or so, and slowly move over the fish.
then start the tear down. the fish will be fine in the temp tank for even a couple days if you get a large sponge filter, which only run $10. 

last thing, have a setup/layout plan in place before you start this. last thing you want to do is tear it all down and not have a clue how you want things to be set up. message me if you got questions


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## onedollarinmywallet (Sep 24, 2013)

Nestle_ said:


> pull everything out down to the old substrate. if you're going to make any hills or higher areas, do as was suggested before. place the old substrate into bags like pantyhose or mesh bags, BUT place it under the new eco complete. the bags will keep it down and not allow it to mix, while doing double duty, holding up a hill and seeding the new substrate.
> just dump the eco complete right in, and if you're new/fresh water looks gross to you then do a 100% water change. depending on how dirty your old gravel is, you may want to do this anyways.
> leave the water level low when you plant, just makes things easy. put the wood in first, and keep it wet while you're rescaping so you dont have issues with floating wood as you refill the water.
> 
> ...


Thanks for the advice about reusing the old gravel to seed the EC as well as to do double duty as a base to create hills, etc. I never thought of that.  From a sizing perspective, would two bags of Eco-Complete be sufficient for a 29 gallon tank?

As for the mesh bag, I found some on eBay (see item #320980799066, for example) which I assume will work? Also, since it has a zipper, will this pose a problem (thinking rust issues here) being submerged in the water? If this will work, then I will get 2-3 of the largest size (16"x12") bags as I currently have about 2-3 inches of gravel (evenly spread out) on my 29G. Thanks!


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## Diana (Jan 14, 2010)

You only need to skim the top layer (perhaps 2-3 rocks deep) to get most of the beneficial bacteria that is in the substrate. Deeper, there is not enough water flow to keep a larger population of bacteria going. 

I also would remove all the current substrate. Do the whole swap in one operation.


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## Nestle_ (Jul 4, 2013)

I wouldn't use the large size mesh bags. it's much easier to use a bunch of small bags.
you can usually find some at a LFS or petco, which saves you time and having to deal with amazon/seller for something that small.
you can even use something like panty hose, go to the dollar store, even cheaper.
going this route, you can put some leftover old substrate into more baggies, and lay them on top of the new setup for a few days, allowing them to spread their good bacteria, and then can be removed once you see a cycle started/going.

also yes, you're two bags of eco are good enough. 
I used 10 in my 90 gallon, and that gave me something close to 3" depth. where you have heavy root feeding plants, I would build up with the old substrate bags. you can even get lava rock, thats sold to use in gas grills, to add more filler and even allow great water flow through it preventing bad gas build up.


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