12-15-2009, 08:18 PM
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Originally Posted by WisFish
This is one area where I differ from Byron. But let me start by saying I have used only gravel in my tanks for the last 30 years.
I agree that plants in general come in two forms. Those that get all or most of their nutrients from the water through their leaves and those that absorb most of their nutrients through their roots. Stems plants seem to fall in the middle. And as Byron pointed out, those plants that get their nutrients from the water through their leaves don't care what the substrate is. The substrate is simply holding the plant down.
But for root feaders, the substrate can make a difference. Gravel offers no benefit to root feeding plants because gravel is unable to hold nutrients. To make up for that deficiency, root tabs are typically used.
Substrates such as Flourite and Eco Complete are designed to hold nutrients for the roots. Plus Flourite has the ability to replentish it's nutrients by absorbing them when ferts are added (I'm told). Some have claimed that the cost of Flourite justifies itself in reduced costs for root tabs. I know that after one year I've already gone through 3 packs of root tabs at $7 a pop. I already have the Flourite for my tank. I just have to find a time when I can tear the tank down.
If you do add Flourite, a mixture of at least 50/50 is recommended. And it really needs to be rinsed well before adding it.
What root tabs are you using? I use Nutrafin's Plant-Gro sticks. In Canada they are $7 for a pack of six (prob $4-5 in USA?), and they supposedly last a year. I only use them next to the larger swords. Enriched substrates are bound to exhaust their nutrients at some point. Diana Walstad, whom I highly respect as most know, discredits all of these substrates in favour of plain soil under a layer of gravel. But I'm not about to follow that for many of the same reasons. There are issues with these substrates, not insurmountable true, but still issues. It's like adding CO2, yes it works, but it means opening another set of doors. Anyway, 20 years of lush planted tanks convinces me that plain gravel is workable. I never used root sticks until this year, so even they are not necessary. You can't get much simpler. B.