clay

[enmac]

Hi folks

i am about to set up my aquarium, and i have many, many questions. i will come to those later. for the time being id like to ask:

does an iron rich substrate have the ability, after relesing iron to my plants, to absorb any fertilizers i might itroduce to the water column ?

thanks

iain

[Plecosterone]

I am not sure if the substrate sold as iron rich would absorb anything. I do know that 6" of clay is used as a "liner" on the bottom of HUGE landfill sites for the reason that it does not absorb or let anything through it.

[enmac]

thanks plecosterone

the reason im asking is, ive been reading up on it, and there are a lot of conflicting advive on substrates. some articles seem to only have gravel or sand as a substrate, others say you wont grow anything in gravel, and again others advocating a nutrient rich substrate. i was wondering what the 'shelf life' of such substrates are. does the tank need to be stripped doen in a few years time and replace the nutrient substrate, or will adding fertilisers etc, replace the depleted stocks of say iron on the substrate. does any substrate have the capacity to absorb these nutrients so plants with roots can then have access to them ?

[Plecosterone]

I use play sand and it works great. Very easy to maintain as you only have to vacuum the surface. I don't even do that too often as the plants like the mulm that gathers around the bottom of them. I am not one for spending money on so called "plant substrates" when sand works fine. Many people do use specialty substrates but I don't really think you need them if ferts are applied when needed. I used to use root tabs but don't even use them anymore and my plants thrive with just water column ferts.

[enmac]

thats just what i wanted to hear. thank you very much plecosterone.

cheers

iain

[phanmc]

Plants can absorb nutrients via roots or through the water column. If you provide enough nutrients through the water column then the substrate becomes less important. A nutrient rich substrate does have the benefit of giving you more flexibility by ensuring that nutrients are always available to plants.

What's in a nutrient rich substrate? Most clay based substrates like Flourite or ADA Aquasoil have a high CEC (cation exchange capacity), the ability to absorb and hold onto positively charged ions which most of the nutrients are. The CEC doesn't diminish and the substrate doesn't need to be replaced. Now excess buildup of mulm can reduce the water flow through the substrate and reduce the substrate's effectiveness so a deep cleaning every few years is a good idea.

[enmac]

Plants can absorb nutrients via roots or through the water column. If you provide enough nutrients through the water column then the substrate becomes less important. A nutrient rich substrate does have the benefit of giving you more flexibility by ensuring that nutrients are always available to plants.

What's in a nutrient rich substrate? Most clay based substrates like Flourite or ADA Aquasoil have a high CEC (cation exchange capacity), the ability to absorb and hold onto positively charged ions which most of the nutrients are. The CEC doesn't diminish and the substrate doesn't need to be replaced. Now excess buildup of mulm can reduce the water flow through the substrate and reduce the substrate's effectiveness so a deep cleaning every few years is a good idea.


thank you phanmc. i was worried about a shelf life for a nutrient rich substrate. you have put my mind to rest. i have read many articles on substrates. some very basic some very detailed, but none answered what you have.

cheers

iain

[Mgamer20o0]

yes you dont need to worry about replacing the nutrient rich substrate.

i use cheap gravel. had great luck with. if you want maximum growth then nutrient rich substrate is prob the best way to go. doesnt mean you wont have great growth with out it.