Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Closest location is right out back.
Scrape away the plants (weeds, in my case) and scoop up a cup or so of soil. Maybe you have to dig a bit to get away from roots.
Pack this into a jar with straight sides (1 pint to 1 quart canning jar works well)
Put a piece of tape vertically on the jar, and mark where the top of the soil is.
Add water and a drop or two of dishwasher detergent (no bubbles)
Shake really well.
Set the jar down and start watching a watch.
At 30 seconds mark on the tape where the soil is.
At 1 minute mark on the tape where the soil is.
At 2 minutes mark on the tape where the soil is.
In a couple of hours mark on the tape where the soil is.
How to read the test results:
At 30 seconds almost all the sand has fallen out.
At 1 minute all the sand has fallen out.
At 2 minutes all the silt has fallen out.
At 2 hours all the useful clay has fallen out.
Anything floating is organic matter- Sticks, roots, leaves... These are not much of a problem to remove when you mineralize the soil.
If the water is only slightly colored, but you can pretty much see through it after 2 hours this is pretty good.
If the water in the jar is still murky the next day, give up. This soil has too much coloidal clay to work well in an aquarium. MAYBE mineralizing it will help, but I doubt it.
Look at the percentages of sand, silt and clay.
This is the amount at the 1 minute, 2 minute and 2 hour marks compared to the total amount of soil you started with.
Good soil for an aquarium will be mostly sand with just a little silt and less clay.
Clay is very important. This is the material that holds the nutrients. High Cationic Exchange Capacity. But it is also hard for the plants to grow in it, hard for the water to move through it.
Over 50% sand is good.
No more than 20% silt, 10% clay.
If there is a LOT of floaters then you might rake through your soil better when you collect it, sift it a couple of times when you start to prepare it, and be ready to skim it every time you re-wet it during the mineralization process. You might need to start with extra soil because you are throwing away quite a bit when there is this much organic matter in it.