Sand VS Sand Capped Gravel

I know there's the great sand vs gravel debate and most people on this forum seem to prefer sand. Can't blame them it's cheap and it looks great. But one thing I have heard is that gravel can be more conducive to root structure. Also since it's so coarse water can flow through it easily. You don't have to stir it either to prevent gas pockets. Yes I know gas isn't a bad thing but it can be annoying. And some fish and snails will stir it up for you. And it's way easier to clean. The annoyances of cleaning gravel seem to be solved by not having it on top, while below it can aerate a bit and give some extra room for roots. Then sand top better for most fish and easier to clean plus you get the nice smooth looks. So shouldn't a tank with gravel base capped with sand be superior? You get the best of both worlds without a lot of the drawbacks.

 

No because they would completely mix over time.

Get a course sand and you'll have 0- issues with compaction or gas forming. Plants will also trans locate oxygen below the substrate to aerate symbiotic aerobic bacteria around the root zones, preventing anaerobic bacteria from creating nasty gas pocket.

A healthy tank should have clean substrate, vacuuming it every water change will also help keep anaerobic bacteria at bay.

 

The sand likely will sift into the gravel, leaving a mixed, not layered substrate.
Nothing against sand substrate, but I prefer natural small grain river gravel.

 

Unfortunately, physics doesn't work that way, the sand will fill in all the spaces between the gravels and you will get the worst of both. Great idea on paper but sadly not a working option.

 

The sand likely will sift into the gravel, leaving a mixed, not layered substrate.
Nothing against sand substrate, but I prefer natural small grain river gravel.

I get that it's going to slowly move down. Gravity is annoying like that. But that's going to take a decent amount of time right? Especially if you went and layered it going from coarse gravel to less and less until you got a sand top. Plus if you did a carpeting plant that should be able to hold everything in place more with an extensive root system no?

 

No harm in trying out your theory. I've haven't read any success stories regarding a gravel / sand substrate mix. You might be the first. On the other hand, keepers mix different gravel types together quite often.
Heres a pic of natural river gravel mixed with white quartz gravel in one of my tanks.

 

No harm in trying out your theory. I've haven't read any success stories regarding a gravel / sand substrate mix. You might be the first. On the other hand, keepers mix different gravel types together quite often.
Heres a pic of natural river gravel mixed with white quartz gravel in one of my tanks. View attachment 654768

I love that gravel mix that looks super nice. I might try that in a future tank. And I haven't tried the gravel/sand mix yet. I thought about it in an existing tank but don't really need to, I don't want to rescape the whole thing. I don't have room for a new tank for a bit. I think it would be interesting to try and I might give it a shot in a year or two here. Just thinking slowly decreasing the granule size might prevent the layers from seeping through very much. Not sure if it would be overly worth it though.