# Filling out substrate volume...



## King of Hyrule (Apr 29, 2013)

You could use simple aquarium to fill the rear of the tank. I also used gravel under my rock features as having costly gravel under them seemed like a real waste of resources.


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## somewhatshocked (Aug 8, 2011)

Another option would be to pick up a 25-50lb bag of black lava rock from Lowes or Home Depot. Usually $3-$5. You could use that beneath the substrate in areas where you want a little more depth. 

On the plus side: it's black just like your substrate.


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## SmittyInFla (May 3, 2013)

Awesome! Thanks for the ideas. Liking the lava rock idea.

While I am asking: Do you folks think the Eco Complete needs to be overtopped with sand?


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## somewhatshocked (Aug 8, 2011)

Nah, sand will eventually sink beneath Eco-Complete. It'll be fine as a stand-alone substrate as long as you use ferts or root tabs (plants depending).

A plus to all the leftover lava rock: you can use it to tie/glue to moss, ferns, anubias and such. I've even used reef epoxy to build larger structures for aquariums. Also nice to have them for flower beds.


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## King of Hyrule (Apr 29, 2013)

Here's a quick picture of my sub-substrate gravel solution. 










You can see the sand, pea gravel, Fluval planting Substrate, MGO potting mix and Eco-Complete all there in one picture. 

Its funny, I never thought of using lava rock as fill. The local lava rocks are my ideal* stone for my rock features. 










*Living in Hawaii, I wanted to source my tanks' hardscape locally; to add a touch of the _islands_ to my tank. There aren't really any native fish I would feel comfortable keep in a tank is with a collection permit (absolutely need for native species). I sources my lava rocks from a construction site, they were going to use it for fill (funny that).


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## SmittyInFla (May 3, 2013)

Update:

Went to Walmart. Picked up a bag of Scott's topsoil, a bag of RED lava (could not locate black, locally), and a bag of play sand. I am not sure I am going to use all these materials, but it does give me options. 

I am thinking: Lava rock to create elevation changes, filled in with the sand to smooth it, and keep the soil and Eco Complete from settling into gaps in the rock. I have not closely inspected the topsoil, so I don't know whether I will need to rinse it yet, or not. I plan to put the topsoil over the rock/sand layer, then the Eco Complete on top.

I do not have any decorative rock, yet, but have an excellent piece of driftwood soaking in treated water, right now. Hopefully, it will be heavy enough after the weekend. I am not planning any drastic elevation changes, but a little will be nice on the end opposite the driftwood. Have not decided on plants, yet...But I do intend to grow some emersed plants along the back of the tank. There will be no hood (the driftwood will rise higher than the frame in the 30 gallon tall), and only shoplights and CFLs to get started.

Does this sound okay? I have been reading for a few weeks, and think I have a fair plan. Am I missing anything?


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## SmittyInFla (May 3, 2013)

So...I bagged some of the lava rock in old knee high stocking. Sort of sausage shaped blivets of lava rock. That way, the rock will hopefully not spread out, when I am planting and moving stuff around. I am going to use sand to fill dead areas, then use the topsoil. Will be topped with the Eco Complete. Still working on anchoring down the driftwood, which may still be a little 'floaty'. I think I can secure it to one of the lava rock bags with fishing line, but it will be tricky filling the tank with dirt and sand with the driftwood in place.


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## lochaber (Jan 23, 2012)

I'm rather fond of bolting driftwood to slate- it gives it enough dense mass to (usually) counteract the buoyancy, it holds the wood in a specific position, and it's fairly cheap/easy. Also, if the slate alone won't hold the driftwood down, the substrate piled on top of it usually will.

Major downside is that it doesn't lend well towards periodic rearrangement - you pretty much have to know how you want the wood when you set it up.


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