[learn2turn]

I always thought that aquarium gravel is way over priced for what it is.

I like the NPT idea of using soil (dirt cheap) and capping it.

I haven't read the book yet but I did order it. Won't be here for a few days.

My guess is the purpose of the cap layer is to allow just enough O2 into the substrate while restricting the rate at which the nutrients come out of the lower soil layer, and to hold the soil down.


Curious about what I could buy at the local home center to use as a top substrate. I already have play sand left over from my kids sand box. It's really fine though. I'm guessing not more than 1mm. Could you use that and just use a thinner layer?

I've also see pea gravel at the home center. That's much bigger, maybe 3-5mm or a bit more. Not wthat's the other extreme. Would that work in a much thicker layer?

 

[Alex123]

Both would work. Diana used sand in her most recent setup posted on this site. It was very thin a couple or so mm thick. I use 3-5mm if not larger on my aquariums. I have it around .5 to 1.5 inches in thickness. I ran out of substrate in my 2nd aquarium so it barely covered the dirt at about half inches in thickness. Both tanks are doing fine.

 

[learn2turn]

Looking again at the sand I have, it's really fine. Much well below 1mm, almost dust like.

The pea gravel I have as some piece maybe 5-8 but much is 8 -15mm.

What would you recommend for thickness on each or is one really just too small and the other too big.

 

[cs_gardener]

I've never used sand so I don't know if what you have would be too small. The recommended particle size is 2-3 mm for the cap. The pea gravel sounds too large. I used something similar once and it was very difficult to plant in, damaged fine roots and stems, and was generally a pain to deal with.

 

[Alex123]

You have two extremes, I suggest somewhere in between. Why don't you buy some small substrate from pet store? Don't need much anyways. I would go no less than beach sand. Or else, mind as well have no substrate at all. Not much difference. Or if most gravel more than quarter inch I also would not recommend.

 

[aquabillpers]

The purpose of the cap over a soil bottom layer is to keep the soil from getting into the water column. The cap sand/gravel particles need to be large enough to allow fish waste and other material to work its way into the soil substrate.

Some sands are too fine. The materials that should get into the substrate instead gather in corners or low places and are unsightly.

I use 2mm - 3mm sand/gravel that i get from a builder's supply store. They call it "builders' gravel/sand" and "blasting gravel". It is quite inexpensive, but here, at least, it is sold only in 100 pound bags.

Bill