Hollow structures and water flow? - The Planted Tank Forum
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post #1 of 4 (permalink) Old 08-02-2013, 05:12 PM Thread Starter
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Hollow structures and water flow?

Hello all,

Thinking about a future project that will require rocks as my primary hardscape. Found this website which offers some good looking artificial rocks:


However, the ones made for aquariums are hollow. I was wondering if the "dead areas" behind/under such rocks would be detrimental to water quality?

Would there be a simple, non-toxic way to fill in the hollows on such decor?

I'd prefer use real rock, but there's not much available in coastal Georgia for collecting or even for sale (such that I can find, anyway).

Alternatively, if anyone knows any good online sources for large, aquarium safe stones, that would be useful info.



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post #2 of 4 (permalink) Old 08-02-2013, 05:18 PM
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I use quikrete concrete in a lot of backgrounds and caves... I'm sure you could fill it with that.

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post #3 of 4 (permalink) Old 08-02-2013, 09:31 PM
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You could use the greatstuff expanding foam, but that will add bouyancy issues. If you do use concrete/cement, you will probably have to seal whatever part is exposed to prevent it from affecting pH and hardness, in addition to waiting for it to cure.

A while back, I had seen an epoxy grout mix in Lowes or something, but I never got around to researching it, I've been wondering if it would be useful for creating backdrops/artificial rocks.

I'd strongly encourage you to make your own - get some epoxy, some sand, and some foam, it's not too difficult. Just stack/carve the foam to the rough shape you like, and then coat it with an epoxy/sand mix.
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post #4 of 4 (permalink) Old 08-03-2013, 09:06 PM
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Have you looked at any landscape supply places? There is most likely at least one in your area that will have rocks for sale.

Indychus, can you give more info on the rocks you've made using quickrete? I've been toying with the idea of making a more FW friendly version of homemade live rock and was wondering how the quickrete was working for you.
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