# "fertilized" gravel?



## Bludypoo (Jun 21, 2014)

Hello All,

I'm very new to planted aquariums but not knew to fishkeeping in general. I've read various threads/pages on substrates and their importance (important) but have a couple of questions.

Most threads I read are about starting a new planted set-up in which fresh everything is bought and a tank must be cycled. I never read any thing about a previously unplanted tank becoming planted.

My questions are: 

1. Will well used gravel work as a substrate? Gravel is full of fishfood/waste (things that normal plants love). Is it the same for underwater plants? Will a well used gravel work as a substrate?

If not, what does it lack? Will granule size make a huge difference? (i know it is pretty important)

2. I've seen instances where people will use only substrate (ADA Amazonia or what have you) and instances where there will be a layer of the substrate with a layer of sand or gravel over top. Is this purely for aesthetics/price? Will using only substrate as your "gravel" be harmful in anyway?

Thanks in advance! If my questions have been covered, please link me to the proper place!!


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## Michael (Jul 20, 2010)

Welcome to APC! You are asking the right questions.

1. Yes. Old tanks with a lot of mulm build-up in the gravel actually develop the same characteristics as soil substrate tanks. There may be specific nutrient deficiencies that need to be corrected, but these aren't likely to be important in a low-tech tank.

2. A cap is necessary for soil substrates to keep the soil in place, prevent it from clouding the water, and give a good anchor for new plants. ADA soil and most of the other proprietary substrates are designed to be used without a cap, but sometimes people add one for aesthetic purposes.


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