New tank, new setup - keep sand or replace?

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Mar 24, 2023
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I'm getting a new 200l aquarium to replace my existing 180l.
The old tank has been setup for years, with sand only substrate, a few plants with root tabs, no soil etc.
The new tank will have aquasoil capped with sand and be heavily planted.
I was thinking of re-using the old sand because a) it must contain lots of lovely bacteria and b) saving money, but then I realised it must be full of all sorts of unslightly grubby mucky stuff underneath the surface and I'm not sure whether rinsing/sieving it to get rid of the crud is realistic?
Should I get new sand or re-use the old sand?
Normally I would rinse it and use it again, but I've no idea what is in it that you are (perhaps wisely) concerned about. Play Sand is inexpensive.

A comment on the plant not use this if you intend substrate level fish like cories and loaches. It can have significant bacterial issues. Its "value" as plant benefit is highly questionable anyway. I was talked into using one of these several years ago, bad mistake and I learned that the catfish sources advising against them were on the mark.
My concern is purely aesthetic - I don't want to end up with the gunk from e.g old rotten roots etc, lying on top of the sand once it's all got mixed up transferring from the old tank to the new tank.
My concern is purely aesthetic - I don't want to end up with the gunk from e.g old rotten roots etc, lying on top of the sand once it's all got mixed up transferring from the old tank to the new tank.
It's probably been in the tank for 10 years at this point
If it's just one material for your whole base, simply empty your tank like 80%, remove all decor, plants and fish, then when there is only the sand with a few inches of water over it give it a thorough stir so to float all the grime, net out anything that floats, take the water out, fill it again with a couple inches of water above the sand, repeat the procedure 2 or 3 times, good to go.

The "modern" way to do substrate for heavily planted tanks and avoid unsightly stuff is to use a soil (top soil, aquasoil, or pond soil, optionally mixed with gravel to avoid anoxic areas) that is organic and does not have harmful chemicals and bag it into filter media bags, which are plastic mesh bags with plastic zipper that the roots have no trouble traveling through. You put that on the bottom and you cover it with sand. You reduce the risk of too many nutrients leaching and causing algae, and you avoid the 2 layers mixing.

Most soils including aquasoil, that tropica black stuff, akadama, are all lighter than sand, so when you plant or move your plants you always end up bringing up some and have to remove it.. Also when you take down your tank it becomes impossible to separate the substrate from the sand.

At home depot or similar you can bring home a bag of top soil for 2-3$ and a bag of pea gravel for 5-6$. Boom nutrient layer done.
Thanks @vince82, yes I'd already decided on the mesh bag method - I started a nano tank a few months ago with pure tropica soil, no cap or bags....and it was a total nightmare, just a tank full of mud!! Capped it with sand/gravel mix which has worked well, but it's black sand/gravel so the occasional bit of soil poking through isn't a problem, with a lighter sand I can see it would look horrible mixed up.
I might get one small bag of a slightly lighter new sand to layer on top of the old sand - just to make sure it looks nice while still keeping most of the bacteria from the older sand. I want to have an exposed area of sand at the a nice caribbean beach for my shrimps to sunbathe on. Maybe some deckchairs/parasols....
I've already got the Tropica soil so I'll stick with it. I've "cycled" it in a tub for a few weeks, so shouldn't cause ammonia spikes.
Disturbed root tabs create a filthy mess. Get new. Argos play sand is £5.50 for 15kg, or £4.99 for 20kg at B&M.
The beneficial bacteria can be transferred via filter media. If you want a bit of insurance add some of the cleaner old substrate in the mesh bag for a while, then remove it after a few weeks.
Thanks, that's good info and that was what I was worried about.
The other bonus is that this means I only have to transfer the fish directly from the old tank to the new tank, without having to transfer them to a container while I move the substrate across. I'm planning to use the old filter as well as the new one for the first few weeks, so there shouldn't really be much of a cycle to speak of.

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