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Discussion Starter · #1 ·
I am wondering if a lighter density soil cap would be easier on plant roots. I tried pea gravel before and that was a nightmare! All of the roots rotted and plants floated to the top. I am using coarse sand now and it fits the bill perfectly, but if I was to use a material that was the same size as course sand but lighter, just enough to keep the soil from mixing, would it let the soil breathe a little better?

I have a crazy idea in my head (They're All crazy:tinfoil3:) to smash lava rock into the same size as my coarse sand. The weight should be significantly reduced, but the surface (pore) area would be increased by a lot. All of the natural water bodies I see in nature have very light silt particles on top, but of course this would be a catastrophe in the aquarium. I guess that is another reason people use a soil cap to keep soil down (besides preventing light/oxidation).

Any thoughts on this? Advantages/Disadvantages? Feel free to share experiences and soil cap preferences, sands/gravels/densities....
 

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I first used EcoComplete as a topper first, because I had it on hand. It looked great, but because it was light, the soil came up every time I worked in it. I still have soil exposed in there. Luckily my soil is old enough that it sticks together now instead of making muddy water. I get some cloudiness when I uproot a lot, but that settles. I have heard other people here say that they didn't like the Shultz Aquatic Soil for it's lightness, but not sure of the details. I have a bag of the Quick Crete sand (about 2mm) for use next time. It's a good color, the MSDS says it's silicate (real sand, so hopefully it won't increase my already high hardness & alkalinity). I haven't bottle tested it, as I don't even have a tank to use it in yet. Also, it was like $5 for 50lbs. It's very dusty out of the bag, though. I know some people don't rinse in El Natural tanks, but I generally give my gravel a quick rinse. The last tank I did with the smallest regular aquarium gravel I could find, but only about an inch. It's doing well. I have plenty of MTS in there. I tried sand in two Nanos, but just made a mess. I had to redo them.
 

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Discussion Starter · #3 ·
What color is the Quick Crete sand? That is dirt cheap! If it is dark in color than it might just save me from wasting an hour of my life hammering lava. I never thought of using that! If it is used for fortifying concrete than I doubt anything unpleasant would have been added to it, but you can never go wrong with a bottle test.

Thanks for sharing! The lava I am thinking of using is dark in color and very cheap, used for gas grills. It has no additives and is inert, sinks immediately in water, about twice as heavy as the red or gray pumice. Thinking about what you said though, if it was still to light than I would be better off with a coarse sand material.
 

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I tried pea gravel before and that was a nightmare! All of the roots rotted and plants floated to the top.QUOTE]

Be careful here to ascribe the problem just to a gravel layer. Uprooted plants mean that something is drastically wrong with your setup. It could be that the soil is too rich. The soil could be over-fertilized with sulfates or its too deep (greater than 1"). It could be that the plants were unsuitable or too weak or that the lighting was insufficient for plants to aerate their root area.

While I don't recommend this, I've used deep gravel caps and sand caps without problems.

Start with an unfertilized soil of 1" and cover it with as little sand or gravel that you can get away with. Plant good growers and give them plenty of light. Get some Malaysian Trumpet Snails, and/or poke the substrate with a sharp object to introduce oxygenated water.

If you've done all this and it hasn't worked, then something else may be causing the problem. In that case, more information and a picture might help.
 

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Discussion Starter · #5 ·
Hi Dwalstad, the tank with root rot (10 gallon) did have MTS and was planted with Sagittaria subulata, Amazon swords babies and duckweed. The cheap soil was .75" thick with a .75" thick gravel cap. I should have been more specific though, the pea gravel was actually more like small landscape rocks, a bit bigger than normal pea gravel. No filter was used and no water movement, and lighting was by the single stock fluorescent bulb.

This tank was fine for a month, the Sagittaria spread all over while the swords did not do much. After a month the new growth was more translucent and plants started floating. I don't think the heavy rocks helped at all but it could have just as easily been a lack of light. If plants don't have enough light, will they begin the fermentation process?

My current NPT is a 5 gal hex with a 15W CFL, no filter. Same soil as used before, about 1.25" thick w/ coarse sand cap at 1.5". Running for close to a year.
Plants: 5 Amazons, 1 crypt, java moss and duckweed.
Fish: 1 Otocinclus, 3 shrimp, tons of MTS
This aquarium started out REAL slow, no fast growers, but once the swords rooted in I haven't worried about a thing. Growth is still slow, but 2 swords are about to break the surface and their growth is picking up, I want to grow them as big as possible and emersed.

My posts are always long winded:brick: Is anyone is still awake? Hello.....?
 

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The Quickrete sand is a good size, but it's light: greys and sandy browns. They have QUIKRETE® Pool Filter Sand (No. 1153) listed on the website, but appears to have the same MSDS as my all-purpose sand (No. 1152). Wonder if it's less dusty or darker? They didn't have this option in the local stores when I was looking for it. Not sure of the price. All of the tanks I've seen pictures of with pool filter media had darker sandy brown and black mix. Hope this helps.
 

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If plants don't have enough light, will they begin the fermentation process?
Plants need oxygen produced by photosynthesis to keep their root zones aerated and detoxified. Fermentation is horribly inefficient, so the plants lose energy fast if they can't photosynthesize.

The problem you had with the 10 gal is a little less clear based on what you've written. Possibly the low lighting, pebble substrate, and no water circulation. I'm also wondering about your water's water hardness.

Glad to hear that your new tank is doing better. With that much light (15 watts CFL over a 5 gal tank) and a soil substrate, those Amazon Swordplants should have filled up the tank within a few months. Again, I'm wondering if your water is a little soft (lacks calcium, magnesium, etc). Amazon Swordplants really thrive in hardwater.
 

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Discussion Starter · #8 ·
Thanks for posting those inventory #'s Mommyeireanne, I will definitely take a look at these!

Thanks for all your help to Diana, my water is VERY soft! PH=6.4, KH=0ppm, GH=10ppm. I have amended the soil with oyster shells and when I got the shrimp I sprinkled a few shells on top of the gravel, but with water this soft I don't know if this is enough. I read the sticky of your water-hardening method, but I don't know what numbers I should aim for! I have never played with the water before so any guidance you can give will be very appreciated! People would kill to have my soft water for discus, but I am always drawn to hard water crypts and nutrient hogging swords. The grass is greener on the other side...:biggrin:
 
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