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Re: [APD] Laterite Substrate

I used to use Dupla laterite a few years ago and remember it as being  
quite fine. If you disturb the substrate, and it's impossible not to  
do that when you uproot and replant stem plants, or any other plant  
for that matter, you will always get some laterite pulled up into the  
water column. When it settles out, it falls back to the substrate and  
since it is so fine it always finds its way back down to the lower  

In fact, when you disturb a substrate containing materials of  
different sizes and relative mass, the smaller and lighter material  
always finds its way to the top when the substrate is disturbed,  
simply because the larger and heavier materials are more resistant to  
movement due to their greater mass. When things settle out, the finer  
material slowly works its way down lower in the mix by 'falling  
through' the crevices between the larger materials.

If you siphon off water for a water change while some laterite is  
disturbed and floating in the water column, you will remove some  
laterite with the water siphoned out so you will hasten depletion  
slightly. Your option is not to do a water change at that point, but  
to do it a few hours or a day later once the laterite has settled  
again. You're going to need to replace laterite eventually and while  
siphoning some off with water when you do a water change will hasten  
the day when you have to do so, it's probably not going to hasten it  
all that much and it really no different in effect than losing some  
liquid nutrients when you do a water change and having to replace them.

It's not something I worried about when I used laterite.

On 14/10/2006, at 7:45 AM, "" <hhatch at sprynet_com>  
<hhatch at sprynet_com> wrote:

> I have a plant tank which is about 2 months old with lots of fast  
> growing
> plants and a laterite substrate. The laterite layer is mixed with  
> sand and
> is covered with another 1.5 -2.0" of sand. . The tank is doing well  
> and
> I've started to do regular pruning of the plants. I have been  
> pulling up
> stem plants and replanting the tops and noticed that when I pull up  
> the
> plants it appears that I am getting laterite into the water column. I
> tested the water and Fe levels jumped up, but came back down after  
> a few
> days.
> Is this going to be a problem for my plants ?  Will the substrate be
> prematurely depleted of nutrients if I continue pulling up stem  
> plants ?
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