In article ,
fusQuanto wrote:

That makes no sense. Who says this?


actually its only the melafix that says it, not the ferts. i figured
the ferts would have the same problem too because the carbon is soaking
up the nutrients? no? im not a chemistry nor biology major so perhaps
you can shed some light. thx


Ok sure. Carbon filters out long-chain organics. Small molocules
pass tight through. In practical terms if you add say methylene
blue to the water and it's dark blue, carbon will filter that
out quite quickly.

But, if you were say to add salt to the tank, carbon wouldn't
touch it. It does not remove salt.

There are no hard and fast rules about this, but in a very rough
sense, rely on carbon not to remove anything transparent, but any
chemical "big" enouh to have color - well that will be filtered out
by carbon.

Melafix is good stuff, but it smells and looks like something that
would be filtered out by carbon. Not so fertilizers.

Having said that there are people who believe carbon will take
things ouf of the water like copper, iron and the like and its
no good for plants. This is slightly true. Carbon will remove
minicsule amnounts of these thigs, so if you never change water
and use carbon for months the plants may suffer. OTOH I've done
this and if they suffer it's really not so you'd notice.


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