Flourite only has trace Fe so it's good for along time before it turns to mush. I've used it for three years at a time without problems but I dose water column ferts so I don't depend on the substrate to do anything but give a good CEC count. The same is true for Eco in my opinion there both about the same in my book.
- Brad
Actually, there is more to flourite than iron as you are stating. Take a look at this link:
http://www.seachem.com/Products/product_pages/Flourite.html There are also alternate sites confirming there is more than iron as well. This is straight from the website:
"Flourite® is a red clay based gravel that is rich in ferric iron. Comparing Flourite® and laterite on the basis of their iron content alone is not a really valid comparison since they are really quite different products (the old apple and oranges argument). Their iron content is going to be roughly pretty similar, but with each the actual content can vary from lot to lot. Since we don't market it as an iron supplement, we don't make any claims on exactly how much iron it delivers to the water per se. What it does do though is provide a rich source of iron (more than enough to last years) for rooting plants... the plants are able to extract the iron from the Flourite®. There are also other features of Flourite which make it superior to laterite: (1) laterite is intended as a substrate supplement, i.e. you add it to your gravel... by itself it is not a suitable substrate because it will quickly break apart into, well, dirt (2) Flourite® is by itself a suitable substrate because
it remains solid, does not fall apart,and can be cleaned and gravel vacuumed without unduly upsetting the substrate."
Now, as for my own experience, I have had it for over a year and it is still rock solid. Also, there are other's to go by:
http://www.vickisaquaticplace.com/p45gal.html
C2C - I haven't regretted the day I purchased flourite. I started out with hornwort and a few basic stems of foxtail. After getting flourite, I was able to grow everything. It is worth the expense in my opinion. I have just gravel tanks, turface and flourite tanks. The flourite is the best with turface close behind.