Gravel or sand?

The same can be said for gravel, it depends entirely on what it is made of, most gravels are inert (in a fashion) the same way sand is, though you sometimes get leaching of silicates with silica sands.

For me the ultimate low budget substrate is clay cat litter capped with fine gravel or sand, clay is an excellent medium for absorbing nutrients, a 10mm layer capped with 50-100mm of sand or gravel has been successful for me even in hi-tech set ups.

I've also used the likes of ADA aquasoil which whilst excellent I can't justify the expense for the results versus something cheaper.

I'm summary though I would go with whatever is best for the fish you intend to keep, bottom dwellers do best with sand so if you're planning on keeping them use sand. Otherwise use whatever you find most aesthetically pleasing. Plants will grow in sand or gravel with no problems. You may need to add fertiliser depending on the chemistry of your source water however when using an inert substrate, as some plants will uptake nutrients more readily from their roots, but most are just as capable of up taking from their leaves too.

I'm going to sit here on a mountain-top and try to look wise. No doubt, I'll fail.
What is sand? What's gravel?
What you buy in California, Australia or Canada is going to be different. My go to locally is pool filter sand, which I would call fine gravel. In 5 weeks, I move 10 hours east, and I'll have to see what I replace my substrates with. Will the filter sand there be anything like what I buy here? I dunno.
There's a local quarry that sells chemically inert sand - great stuff for my softwater tanks. One local hardware chain sells a sand that raises water hardness, and another sells sand that rinses out to about 1/3 the volume you pay for.
Heavier grains can go with fast water flow, smaller grains with quieter habitats. So on and so on.
It's tough for a beginner who wants easily digested answers, but your sand can be my gravel and vice versa. So look around, see what you like and use it.

itiwhetu said:

The main problem with sand is that it is Silica. Which adds nothing to the tank, with gravel you manage to get the benefit of lots of minerals being added to your tank. As I see it sand is inert, which is why you then must add fertilizers so your plants will grow.

Click to expand...

I've never added ferts to this tank, with Petco sand

Slaphppy7 said:

I've never added ferts to this tank, with Petco sand

Click to expand...

Wow! What plant is that?

CuriousFins said:

Wow! What plant is that?

Click to expand...

Cryptocoryne Wendtii​

I'm constantly culling them out of the tank

Slaphppy7 said:

I've never added ferts to this tank, with Petco sand

Click to expand...

Which shows that fertilizers are not needed in aquariums, like I have been saying all along. It most probably also shows that the addition of fertilizers do more harm to the plants than good.

itiwhetu said:

Which shows that fertilizers are not needed in aquariums, like I have been saying all along. It most probably also shows that the addition of fertilizers do more harm to the plants than good.

Click to expand...

"As I see it sand is inert, which is why you then must add fertilizers so your plants will grow."

This is contradictory to your quoted statement.