Flourite - does it work?

So I just typed up a whole topic and then somehow accidentally hit the back button, so now I have to do this again...

Long story short, I have been looking for reliable data that shows that Flourite really helps plants grow better, but guess what I found? Pretty much nothing!

All I can find is either vendor pages (which are designed to make you buy, so of course they will say it works) or forum posts by people who claim that Flourite works better for them than "x" other substrate. I don't think either of these sources can be trusted, owing to the hundreds of variables which can differ between tanks, so I turn to you folks and inquire:

has anyone ever done a 50/50 flourite/gravel tank a la dustinsfishtanks' 50/50? By that I mean not mixed 50/50, but one half of the footprint Flourite, the other half an inert gravel of similar size/shape/color. If not, I think this might be my next project, so that I can see for myself whether this stuff makes plants grow better. Even then, I'm not sure it would be worth the money.... But anyone who wants to donate some flourite for an experiment would have a friend for life

So, my main question is: Is there any roughly scientific evidence which shows Flourite having a significant advantage over similarly sized/shaped gravel/sand?

Secondarily, what has your experience with Flourite been? Do you think it improved your plant growth? Was it worth the extra money? Any problems encountered with it?

I think the conventional wisdom is that it has more surface area for nutrients to collect and helps keep roots oxygenated.

Both of my eco-complete tanks (similar stuff) are doing pretty well as far as plants go; they've been running for years now.

Here you are my friend.

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Seachums has a few different Fluorite products. In my largest tank I mix them.

I have roughly 300lbs of Seachums Fluorite sand and gravel in my house. I know from over 6 years of using this stuff it is a very good substrate to use for planted tanks. When I started in this hobby I started with normal aquarium gravels. Then, began focusing on planted tanks. It does make a difference. Once you set Fluorite in you never have to change substrate again for any reason I can think of.

pbmax wrote:I think the conventional wisdom is that it has more surface area for nutrients to collect and helps keep roots oxygenated.

Yeah, this is the type of thing I have heard (and of course Seachem claims), but what is the mechanism by which it helps keep roots oxygenated? I understand the surface area aspect, and I guess depending on shape there could be marginally more oxygen flow down to the roots, but that is really just a function of grain size/shape... I guess maybe the combination makes it superior to a lot of other substrates?

I'm really just trying to understand how it works, because I guess I could see myself using it in the future possibly. Right now I have a couple of different substrates that are all smaller than gravel but rough compared to most sand, and it seems to be working out great, even without root tabs or anything. I'm just trying to understand the reason this stuff works better, if it does.

Aquarium gravel, or substrate, is commonly composed of quartz or other lime-free minerals. And may be naturally colored or dyed, and may have a polymer seal to ensure it does not affect water chemistry.

Flourish substrate is a porous clay with these elements Aluminum Barium Calcium Cobalt Chromium Copper Iron Potassium Magnesium Manganese Sodium Nickel Vanadium Zinc. Everything a plant may need. It also doesn't alter PH. Natural buffers like aquarium woods will lower PH, or crushed coral will raise it. Since all my planted tanks have woods I use coral to counter low PH & maintain PH @ about 6.8 (dont know why I through that in).

I have a mixture of flourite and gravel in my 10 gallon. I wish the gravel was closer to the same size, but either way it is mixed. Growth seems fine in my plants. I have stargrass that stays mostly green and cryptocorynes, etc. I do use root tabs for the crypts though. I've also noticed good root growth on my Bacopa caroliniana when I had to pull it up.

My 7 gallon bowfront is only flourite. I still have about a gallon's worth plus a whole unopened bag left. I've noticed a runner from one of my plants that I've not had too much luck in my 36 gallon bowfront (just in sand). That is only plant I can speak for.

Indeed; flourite, while it may contain some minerals, isn't considered a nutritive substrate.  And what little it has will become depleted over time.  You still have to use root tabs with it if you have root feeders and don't have enough nutrients working their way down from the water column into the substrate.  I occasionally add root tabs to my eco complete tanks, but the large grain size allows a lot of good stuff to work its way down to be used by root feeders.  I keep multiple types of crypts, pygmy chain sword, and anubias in those tanks without much trouble.

The planted tank trend seems to be away from flourite and eco complete type substrates and more toward dirted tanks - be they walstad-type, mineralized soil, aquasoil amazonia, etc. This doesn't mean the old stuff doesn't work.

pbmax wrote:Indeed; flourite, while it may contain some minerals, isn't considered a nutritive substrate.  And what little it has will become depleted over time.  You still have to use root tabs with it if you have root feeders and don't have enough nutrients working their way down from the water column into the substrate.  I occasionally add root tabs to my eco complete tanks, but the large grain size allows a lot of good stuff to work its way down to be used by root feeders.  I keep multiple types of crypts, pygmy chain sword, and anubias in those tanks without much trouble.

The planted tank trend seems to be away from flourite and eco complete type substrates and more toward dirted tanks - be they walstad-type, mineralized soil, aquasoil amazonia, etc.  This doesn't mean the old stuff doesn't work.

IDK, Ive been using the same Flourite substrate for over 5 years now & havent noticed any decline in performance.
I will say though it seems there is better growth when I dont do gravel vacs. Thinking this has to do with decomposing organic material that works itself into the substrate. I can literally tell a difference after a few months. Then if I do a gravel vac the siphon tube is just black with sediments. At that time I have to go super slow not to black out the tank and kill sincitive fish (learned the hard way).
Will add I have always used CO2 injection. In the last couple of months I have been using root tabs and have seen an explosion in plant growth.

It seems to me that the grain size and surface area of flourite and eco-complete lend it toward better root growth as opposed to the supposed nutrient content of the stuff itself.

I don't use CO2 and I don't regularly use root tabs and growth is still good. I also have decent root feeder growth in sand tanks, though not as good as in my eco-complete tanks. It definitely works - better than sand. But it doesn't work as well as dirt, in my experience.

Hi LuminousAphid,

LuminousAphid wrote:Long story short, I have been looking for reliable data that shows that Flourite really helps plants grow better, but guess what I found? Pretty much nothing!

So, my main question is: Is there any roughly scientific evidence which shows Flourite having a significant advantage over similarly sized/shaped gravel/sand?

Secondarily, what has your experience with Flourite been? Do you think it improved your plant growth? Was it worth the extra money? Any problems encountered with it?

Per Seachem:

Flourite® is a specially fracted, stable porous clay gravel for the natural planted aquarium.

Flourite is a heated clay based product that contains a multitude of the micro-nutrients required by plants; and assuming it easily releases those nutrients to plant roots it is good.  However checking the information on the product Flourish shows it has no nitrogen, potassium, phosphorus so those critical macro-nutrients have to be added to the water column but the user.  Unfortunately Flourite has a lower CEC (cation exchange capacity) which means the macro-nutrients that are added to the water column are not well absorbed and made available to plants in the root zone.

CEC Values of various materials

<0.1 Clean sand / Gravel
1.7 Fluorite
24.3 Soil
27.0 Softer fired clay products ( Safe-T-Sorb / Turface / Soilmaster Select / cat litter)
** ADA Aquasoil also has a high CEC but I have no number

I guess in answer to your question if there is an advantage for using Flourite over sand or gravel?  I would have to say 'Yes'.

That said, if I were to use Flourite I would use as a source of micro-nutrients in conjunction with a substrate with a high CEC value.

Very nice Roy, thank you for providing that. It seems Seachems Flourish substrate products differ from dark gravel, sand, Onyx, ECT..

I have already mixed a couple of the Seachems substrates to (in theory) boost nurturance's provided by the individual substrates since they all seem different.

ive had good luck with it. that doesnt mean i coulldnt have had better luck with other substrates, but even with used flourite my plants were going nuts

i put 30 lbs in the 90gal last night. pulled out a 5 gal bucket of sand, cut the tank right down the middle and replaced the left side. need two more bags, but the only to remaining bags in federal way are the red stuff, and i wanna go dark

Thanks a lot Roy, that is extremely helpful. And thanks to the rest of you as well for replying with your experiences, it's giving me a much better picture of the whole range of different substrates.

I am interested in the other clay products, since they have such a high CEC... and who first thought of using cat litter for a planted tank? That's genius! I love homebrew solutions like that

I will have to look into some of the other substrates that Roy mentioned, I'm not sure I'm ready for dirt yet because of the whole "move one thing and your water is cloudy with dirt" aspect of it, but something with a higher CEC that isn't so dirty might be ideal

Also, how much impact on nutrient absorption does CEC have? Looking at just the CEC numbers, it looks like soil and other high CEC materials are many times better than flourite or sand/gravel... but we all know that sand does allow at least some nutrients to be absorbed by roots, or some of our plants would just die. So CEC isn't the whole equation, obviously, but it would be interesting to know how much of an impact using a high CEC substrate has on nutrient uptake in practical terms. 2x as much nutrient uptake? 4x? 10x?

I don't expect answers to all of this, I am just sort of wondering out loud here. I will have to look into eco complete, I thought it was a type of soil before now.

I routinely move plants in my dirted tank and have never clouded the water. The way I process my minteralized soil it basically congeals under the sand. Imagine mixing dirt with Jello. When I want to pull up a plant I just slowly pull it up, if I notice dirt starting to come up I get as much root up as I can without disturbing it too drastically and then cut the roots and re-plant. Works great. The dirt almost instantly settles and the shrimp pick through it and work it back into the sand.

And that my 2¢ on that

Seattle_Aquarist wrote:27.0 Softer fired clay products ( Safe-T-Sorb / Turface / Soilmaster Select / cat litter)

FWIW, I've seen several threads on TPT recently about STS breaking down to slurry after undetermined amounts of time in several aquariums. Might have something to do with the high CEC, but I'm not sure...