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This question only just came up to me about a week ago. I read this in an article and a couple videos talking about how one shouldn't use sand in planted aquariums. They go on to talk about how sand chokes out plan roots and inhibits them from breathing and spreading and allowing water to circulate around the roots. I currently use a sand cap on all my dirted tanks. Have I doomed all my plants to death?
 

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Depends on the type of sand. Sands contain silicate which can cause Diatoms/brown Algae. Sand will compact as time passes causing what you stated in your post, poking the substrate may help prevent air pocket or add some MTS.
 

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The sand most often sold as Play Sand has fine particles of mixed sizes. These mixed sizes tend to settle and fill all the voids between the grains, which slows or stops the water movement through the substrate. The microorganisms in the substrate use up the oxygen faster than it gets replaced, so the anaerobic organisms thrive. Mostly these produce hydrogen sulfide, which is toxic to fish and plants.

Other sands are sifted or graded so the particles are pretty close to the same size. Pool filter sand is like this, often 20-30 mesh (20 pieces per inch or 30 pieces per inch). Sand blasting media is available in different grits. Some masonry sand is graded, and you can get bagged sand in different particle sizes in stores that sell rocks, bricks, concrete and similar products. Coarser than about 1/8" grit (#8, 8 mesh) starts looking more like a fine gravel in the tank, but may suit you.
When most of the particles are the same size the voids stay open, allowing reasonable water flow. This enhances the exchange of gases, and brings fertilizers down into the root zone (if you add them to the water).

Most sand is silica sand. Yes, it supports diatoms. The effect goes away after a while. It is usually off white, sometimes with dark grains.
Other materials can be sand sized, and the physical properties are the same: If the particles are all one size, this is best. Dolomite sand is one example of a product that is available in masonry stores. The main ingredient is magnesium carbonate. This dissolves in the water and adds to the GH and KH, and raises the pH. This can be a problem for soft water fish, but is OK for hard water tanks. Bright, sparkly white.
Coral sand is ground coral. It is available in different sizes. Coral is mostly calcium carbonate with a few other minerals. This also will dissolve in acidic water and raise the GH, KH and pH. I have coral sand in several tanks. Plants grow fine in it. Off white, slightly tan.
There is a product available in the swimming pool trades. It is often quartz, sand-sized particles, that are added to the finish coat inside a pool to make it different colors. 3M Colorquartz was one of them that you will find references to. Unfortunately 3M is no longer making their product, but other companies are making similar products. Pebble Tek is one. Some of their materials have sea shells added for more sparkle. These will dissolve in the aquarium and make the water more alkaline. These quartz products are very dense and hold the plants down well. I have one of the black ones in a tank, and it looks really nice. There are other colors.
 

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I find if you live in the PacNorWet, and you can get river sand from the West flowing rivers west-side of the Cascades, that this gravel is mostly worn, old volcanic rock and debris, and it's really good aquarium gravel if you can source it for cheap. Usually dark colored, reddish brown and near blacks.
 

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This question only just came up to me about a week ago. I read this in an article and a couple videos talking about how one shouldn't use sand in planted aquariums. They go on to talk about how sand chokes out plan roots and inhibits them from breathing and spreading and allowing water to circulate around the roots. I currently use a sand cap on all my dirted tanks. Have I doomed all my plants to death?

Dont overthink it too much. Your substrate is dirt that happens to have a bit of sand on top. So the roots in your tank are growing in dirt.

Do you have a problem with your tank? Are your plants dying? Or are the interwebz gurus convincing you that you may potentially have a problem one day? I chalk this one up to lots of people making excuses for why they didnt succeed. If you throw some inert substrate (like sand) in your tank and expect it to grow plants like that you're not likely to get great results. So the answer must be that the sand is bad. Every substrate can potentially "choke" out a plants roots and cause anaerobic pockets. A healthy root system should take care of that though. That being said, it never hurts to poke around in the substrate a bit to make sure no pockets are forming though.

Ever see a lake or pond that didn't have some sand on the bottom even if its mixed in with the dirt and other substances?
 

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Mts

A lot of people don't like them, but Malaysian Trumpet snails help aerate the sand. To me they are great. They keep everything clean, they don't eat the plants, they aerate the sand, they let me know when water quality is bad (the climb up the side of the tank to the water line when this happens, you never really seen them because they are usually burrow in the sand, and they let me know when I'm over feeding. Note: when you over feed their population explodes. This is the reason most people don't like them. However, if you just decrease your amount of feeding, they die off. In fact, when I didn't want them long ago, I just didn't feed my fish for a few days and they were all gone. <br />
Hope this helps
 

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I also have no problem with trumpet snails, they don't breed fast, and don't poop on everything like pond snails. (actually I find they slow the population growth of pond snails)
My experiments with using plain sand, works for about 6 weeks to 2 months, then you see all growth taper off, stem plants dropping their lower leaves and growing roots, with new leaves getting smaller and smaller.
 
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