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Redoing substrate... sand on top of gravel

MichaelJ

MichaelJ

Member
Joined
9 Feb 2021
Messages
3,547
Location
Minnesota, USA
Hello,

Ok, this is something I've been pondering for a while. I have gravel in both my tanks - It's CaribSea Red I always hated the look of it to be honest and it is too coarse. Starting with one tank - low-tech, densely planted, fish (no invertebrates) tank, I am planning to remove a good layer of the gravel and add some nice looking finer sand (1.0-2.0 mm) such as this CaribSea Sunset Gold on top... other ideas are welcome as I haven't made up my mind yet - just don't want something that is white, pitch black or coarse and not too fine either as it limits flow - and it must be inert!

Here is my 11 step action-plan:

- Drain about 30L of the water for a holding container and reuse

- Remove all plants (no way I will be able to catch the fish before I remove the plants 🙂 )

- Catch and transfer fish to the 30L aerated and "heated" container - The stock is a pair of large Angle fish, 6-7 Rummy nose tetras, 4 really old bleeding heart tetras and a couple of Ottos.

- Drain most of the remaining water (until gravel is clear of water).

- Remove about 1/3rd of the existing gravel (about 1 inch.)

- Remove additional water exposed after removal of 1/3rd of the gravel

- Add the new (pre-cleaned) sand on top

- Add fresh perfectly matching pre-heated water (it would amount to a ~75% WC).

- Add plants - some of which will be new

- Let tank settle for a couple of hours

- Add fish including the water from the holding container (old tank water)

I think the whole process will take about 4-5 hours.

Anything else anyone can think of that I need to consider?

Cheers,
Michael
 
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Hello @MichaelJ - you do love a challenge!

My view for what it is worth:
  1. As long as your filter is mature, I would not worry too much about the water aspect. A few months back, I made an 80% water change with no ill effects on livestock.
  2. I would just keep an eye on any ammonia climb for the holding tank, but that should not be a problem during your allocated time.
  3. You are already pre-cleaning the sand, but there is a small risk that it will continue to be cloudy even with a thorough cleaning. I don't think that is an insurmountable issue, though.
  4. I probably would not feed on the day of the process. Just skip that until the next day. Perhaps keep lights off/low, too, for the day to minimise stress.
  5. Take the opportunity to perform a sniff test on your gravel (deep-level extract and sniff!) and check there are no horrible smells. (Whilst you are there, you might as well!).
  6. Take some readings and keep an eye on the post-process day and ensure all is well.
Good luck - I hope it all goes well!
 
If your gravel is not too large, you can siphon it out, which means that most of the dirt will go with it and not damage the rest of the tank.

If your gravel is too large, it will probably not have much dirt on the top layer and you can remove it with a shovel of some sort and siphon water just to pick up any excess dirt that may float around.

In these cases, I would try and do everything without removing the fishes and only removing easy to root plants. If the tank is large enough, you could do this in two sessions, a few days apart, to minimize the stress on the fish.
 
Bradders said:
Hello @MichaelJ - you do love a challenge!

My view for what it is worth:
  1. As long as your filter is mature, I would not worry too much about the water aspect. A few months back, I made an 80% water change with no ill effects on livestock.
Click to expand...
The tanks been running for over 4 years so the old substrate - which I am still keeping 2/3rd of - is very, very mature so I am not too worried about that part. I wouldn't consider my filters mature in the traditional sense - its two HOBs with sponges only (no bio media) and two internal circulation filters with sponges as well... all of which gets cleaned vigorously every 3-4 weeks, but during the refurbish I wont be cleaning the filters.

Bradders said:
  1. I would just keep an eye on any ammonia climb for the holding tank, but that should not be a problem during your allocated time.
Click to expand...
Right. Shouldn't be an issue for 4-5 hours.

Bradders said:
  1. You are already pre-cleaning the sand, but there is a small risk that it will continue to be cloudy even with a thorough cleaning. I don't think that is an insurmountable issue, though.
Click to expand...
I am actually going to deploy my trusted Marineland Waterpolisher to mop up floating sediment. Its remarkably efficient for a 150 L tank.

Bradders said:
  1. I probably would not feed on the day of the process. Just skip that until the next day. Perhaps keep lights off/low, too, for the day to minimise stress.
Click to expand...
Good point. The livestock will be spooked at least for a day and wont be feeling much like eating anyway.

Bradders said:
  1. Take the opportunity to perform a sniff test on your gravel (deep-level extract and sniff!) and check there are no horrible smells. (Whilst you are there, you might as well!).
Click to expand...
I think the microbial community in my gravel is in pretty good shape and I expect it to smell pretty swampy. If I smells anything unusual - such as Hydrogen sulfide (H2S) as in rotten eggs - thats a different story.
Bradders said:
  1. Take some readings and keep an eye on the post-process day and ensure all is well.
Good luck - I hope it all goes well!
Click to expand...
Thanks Mate!

Cheers,
Michael
 
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LMuhlen said:
If your gravel is not too large, you can siphon it out, which means that most of the dirt will go with it and not damage the rest of the tank.
Click to expand...
With a wider hose that could actually be an option! Never though of that - at least that would work partially until the water level falls short.

LMuhlen said:
If your gravel is too large, it will probably not have much dirt on the top layer and you can remove it with a shovel of some sort and siphon water just to pick up any excess dirt that may float around.

In these cases, I would try and do everything without removing the fishes and only removing easy to root plants. If the tank is large enough, you could do this in two sessions, a few days apart, to minimize the stress on the fish.
Click to expand...
I want to get this done in one sitting... I think I am just going to rip off the band-aid and of course be as gentle as possible with the fish. Thats why I want to remove the plants first so I don't have to worry about having to chase them down and stress them unnecessarily and furthermore making it easier to re-scape the tank without having the livestock going through the horror of me working on the tank.

Thanks for the advice.

Cheers,
Michael
 
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Hi Michael,
I was just wondering if it might be worth putting the existing substrate (Eco Complete) that you intend to reuse into mesh bags to avoid it making an appearance later on, we all like moving plants around especially at start-up. I've got lumps of white/grey pumice from the Power Sand which is the bottom layer sitting on top of my nice black/dark brown AS, I'm also pretty sure some of it has worked it's way up by itself.
 
I second that. A divider might cause less disruption than putting the gravel in bags. Apart from soil, which is pretty good at staying under sand, any gravel is liable to re-emerge. Might this even be a time to switch to remove all gravel and switch to a dirted tank ? Too major an operation? With your range of filters I'd expect you could keep the fish happy in their refuge, and also get the tank going again fast. Dirt under sand is quite stable in my experience.
 
A third vote for that @MichaelJ - all your gravel will migrate up to the top of the sand eventually unless you take measures to keep it in place, a layer of fine plastic mesh over the top before adding the sand should do the trick, or bagging the gravel up as others have suggested (though I imagine that's going to be very time consuming).

Also stick with your first choice substrate of the Caribsea Sunset Gold - it's a lovely looking sand mix that I tried for months to get hold of in the UK to no avail.

Finally I'd plan for a larger container than 30 litres to house those two Angels. Even on a temporary basis that's way too small.
 
bazz said:
Hi Michael,
I was just wondering if it might be worth putting the existing substrate (Eco Complete) that you intend to reuse into mesh bags to avoid it making an appearance later on, we all like moving plants around especially at start-up. I've got lumps of white/grey pumice from the Power Sand which is the bottom layer sitting on top of my nice black/dark brown AS, I'm also pretty sure some of it has worked it's way up by itself.
Click to expand...
AlecF said:
I second that. A divider might cause less disruption than putting the gravel in bags. Apart from soil, which is pretty good at staying under sand, any gravel is liable to re-emerge.
Click to expand...
Wookii said:
A third vote for that @MichaelJ - all your gravel will migrate up to the top of the sand eventually unless you take measures to keep it in place, a layer of fine plastic mesh over the top before adding the sand should do the trick
Click to expand...

Thanks for the advise. Makes a lot of sense. I think I am going for the mesh over the remaining layer of Eco Complete. As mentioned, I am keeping about 2/3rd of the existing and very mature gravel substrate and I will be trying to remove about 1 inch. (average) without disturbing the lower layer too much. While probably more ideal, bagging it would probably cause too much disruption. The grain size of the existing gravel is about 3-6 mm. So I guess a mesh size of about or little less than 3 mm should work. I think that would require me to add a very thick layer of the sand in order to be able to get the plants back in the substrate?

Wookii said:
Also stick with your first choice substrate of the Caribsea Sunset Gold - it's a lovely looking sand mix that I tried for months to get hold of in the UK to no avail.
Click to expand...
Yes, it is great looking... I've seen a mature tank with it and looks great. One thing that worries me about the Sunset Gold is the grain size of 0.25 - 1.0 mm... It just seems a bit too fine and might inhibit nutrient distribution and have a tendency to clump making it hard for roots to penetrate. Also, I think with that tiny grain size the sand may eventually make its way down in the gravel... Any alternative ideas for similar sand with a larger grain size - say 2.0-3.0 mm. ?

Wookii said:
Finally I'd plan for a larger container than 30 litres to house those two Angels. Even on a temporary basis that's way too small.
Click to expand...
Noted. Even though I only expect them to sit there for 4-5 hours, I think I might be able to use a larger storage container.

Cheers,
Michael
 
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One thing, cleverer people may have answers to this, but I have found even a grid separator can ride up, and it is really worth weighting this, or even having some way it is secured to the tank base, to prevent this. I had to add extra sand when my grid rose up, when I was trying to clean algae off the glass, below the level of the sand, and the grid became caught in the razor. One solution can be bags to which a grid is attached. But I hear you about bags. Maybe a grid with some lead weights on top. It's worth trying to find a grid that isn't too heavy, so roots can easily find a way through.
 
MichaelJ said:
One thing that worries me about the Sunset Gold is the grain size of 0.25 - 1.0 mm
Click to expand...

It shouldn't be an issue, my Hugo Kamishi sand is a similar size, and my plants have no problem rooting in it. I have used silver sand in the past which is 0.15-0.25mm grain size, and that was a bit small to be honest, and I did have some black stinky patches in the deeper substrate when I broke the tank down.
 
Wookii said:
It shouldn't be an issue, my Hugo Kamishi sand is a similar size
Click to expand...
What specific Hugo Kamishi sand are you using?

Wookii said:
, and my plants have no problem rooting in it. I have used silver sand in the past which is 0.15-0.25mm grain size, and that was a bit small to be honest, and I did have some black stinky patches in the deeper substrate when I broke the tank down.
Click to expand...
Thanks @Wookii ... This is helpful. I'm just trying to get all the info and advice I can before doing the re-scape as this will have to last for another +4 years and possibly longer.

My main concern is really that if I use say a 2 mm mesh on top of the old gravel it would require me to use quite a thick layer of the new sand/gravel in order to be able to physically root my plants. Secondly, with the small grain size of the new sand relative to the old 3-5 mm gravel a lot(?) of the sand will eventually sift through the lower layer.

Cheers,
Michael
 
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