Possible new 55G soon. Substrate for low tech..

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I'm thinking of getting a fluval 55g *(or a corner bow front) in the near future. I am a fan of heavily planted tanks (like my nanos' 5.5/12g) So far i have been using rock substrate.

I was thinking of using blasting media for the 55g tank. For doing a low tech setup should i be using dirt instead? or dirt capped with blasting media?

I'm planning on doing lots of plants with shrimp and a massive army of CPD's for the inhabitants.