# Fluorite Black Sand as cap?



## Triport (Sep 3, 2017)

Is there a specific plant you want to grow that requires nutrient rich substrate? In my current tanks I just use sand and everything does fine with just regular fertilizing (no root tabs). I had an old tank with just Flourite black sand and it did well too. Short video of it:


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## mattsoccer20 (Nov 8, 2011)

Triport said:


> Is there a specific plant you want to grow that requires nutrient rich substrate? In my current tanks I just use sand and everything does fine with just regular fertilizing (no root tabs). I had an old tank with just Flourite black sand and it did well too. Short video of it:


I'm trying to do a carpet of dwarf hair grass. Your tank looks great!


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## johnson18 (Apr 29, 2011)

I’ve used Fluorite Black Sand as a cap over soil several times with good results. I’ve also used Black Diamond Blasting Sand as soil cap as well.

Fluorite Is not nutrient rich though. It has a high cation exchange capacity which basically means it will hold nutrients in a way that will allow them to be easily accessed by the plant roots. You still have to add those nutrients into your tank or substrate though. I have used the fluorite sand in all of my soil tanks for this exact reason. Using soil substrate like, miracle gro, I usually mix Fluorite in at about a 25% ratio. Then I cap the soil with either more Fluorite(if I have it) it usually BDBS. 

Maybe I missed it, but what was your issue with ADA Aquasoil?


Sent from my iPhone using Tapatalk


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## mattsoccer20 (Nov 8, 2011)

johnson18 said:


> I’ve used Fluorite Black Sand as a cap over soil several times with good results. I’ve also used Black Diamond Blasting Sand as soil cap as well.
> 
> Fluorite Is not nutrient rich though. It has a high cation exchange capacity which basically means it will hold nutrients in a way that will allow them to be easily accessed by the plant roots. You still have to add those nutrients into your tank or substrate though. I have used the fluorite sand in all of my soil tanks for this exact reason. Using soil substrate like, miracle gro, I usually mix Fluorite in at about a 25% ratio. Then I cap the soil with either more Fluorite(if I have it) it usually BDBS.
> 
> ...


So it sounds like flourite black sand is the way to go over normal sand caps or black diamond blasting sand? Thanks for the help!

But with my aqua soil, apparently you are not supposed to rinse it at all before use (which I did because I didn't read the bag lol) or it'll be pretty much unuseable because it'll just keep turning your water dark brown


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## Chlorophile (Aug 2, 2011)

Petco sometimes has fluval stratum, ada aquasoil is amazing for dhg too.
I don't often see good carpets of dhg in sand but if you do try it I'd make sure you go with eleocharis acicularis and not parvula as it has always grown much more aggressively for me.

Miracle grow organic under sand can do very well also with no fertilizer if your lighting is low enough.

Amazon prime has the tropica soil which is also Excellent!

Your choices are endless really however if you want to do a scape with some depth and a sloping substrate, sand is probably not the best choice as it has a lot of tendency to drift and flatten


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## mattsoccer20 (Nov 8, 2011)

Chlorophile said:


> Petco sometimes has fluval stratum, ada aquasoil is amazing for dhg too.
> I don't often see good carpets of dhg in sand but if you do try it I'd make sure you go with eleocharis acicularis and not parvula as it has always grown much more aggressively for me.
> 
> Miracle grow organic under sand can do very well also with no fertilizer if your lighting is low enough.
> ...


Wow I didn't know petco carried that, I'll have to stop in! So you see a lot of DHG carpets in stratum or ada soil then (compared to sand)? I don't know anything about tropica soil, I'll have to look into that. Thanks for help!


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## Nlewis (Dec 1, 2015)

Sounds like an expensive cap. You can grow DHG in inert sand with regular column dosing.


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## Kubla (Jan 5, 2014)

mattsoccer20 said:


> So after a failed attempt at ADA soil and me having limited time I am looking for a replacement substrate. I have always liked fluorite black sand so I was thinking of trying and using that as a cap over dirt or using some red clay as a bottom layer for nutrients. Not sure how well it would work as a cap however? Trying to find a cheaper and faster cycling substrate that is nutrient rich for my tank (trying to do hightech plants):grin2: Any advise would be great!


I'm curious why Aquasoil didn't work for you. It's supposed to be one of the best substrates for dhg.

Bump:


mattsoccer20 said:


> So after a failed attempt at ADA soil and me having limited time I am looking for a replacement substrate. I have always liked fluorite black sand so I was thinking of trying and using that as a cap over dirt or using some red clay as a bottom layer for nutrients. Not sure how well it would work as a cap however? Trying to find a cheaper and faster cycling substrate that is nutrient rich for my tank (trying to do hightech plants):grin2: Any advise would be great!





johnson18 said:


> I’ve used Fluorite Black Sand as a cap over soil several times with good results. I’ve also used Black Diamond Blasting Sand as soil cap as well.
> 
> Fluorite Is not nutrient rich though. It has a high cation exchange capacity which basically means it will hold nutrients in a way that will allow them to be easily accessed by the plant roots. You still have to add those nutrients into your tank or substrate though. I have used the fluorite sand in all of my soil tanks for this exact reason. Using soil substrate like, miracle gro, I usually mix Fluorite in at about a 25% ratio. Then I cap the soil with either more Fluorite(if I have it) it usually BDBS.
> 
> ...


I keep seeing this put out there and it's one of the reasons I chose flourite, unfortunately it's fake news! I've seen one quantitative test of flourite for cec and it's extremely low.


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## Vieve (Sep 25, 2016)

Mattsoccer20 how'd this work out for you? I realize this is a fairly old thread but I'm considering doing the same with my 100 gallon. It's already an established tank so once I go for it I'm not changing it again!


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## kbear15 (Nov 2, 2021)

Vieve said:


> Mattsoccer20 how'd this work out for you? I realize this is a fairly old thread but I'm considering doing the same with my 100 gallon. It's already an established tank so once I go for it I'm not changing it again!


Did you end up going with this, Vieve? Setting up a 125 gallon this way right now - potting soil with Flourite Black Sand as a cap. Would be great to know how it went before being committed to it!


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