Originally Posted by Crepe
My 305 has:
bottom layer: 2cm of course sponge the rest with bio rings,
middle : bio rings
top: bio rings
No water problems here.
I use fluval's biomax. Took three boxes to fill it...
And at the above poster: Materials sequestered by carbon are practically there forever. It takes furnace temperatures of several hundred to several thousand degrees to cause carbon to release what it's holding on to. It will never leech things back into the water unless you had an aquarium of lava or something.
Interesting information you presented and as such it set me on a search to find out why so much misinformation is passed around contradicting what you posted. You are, in general terms correct with a few discrepancies in how you presented it. Here's what I found out and confirmed in a couple well written articles.
First off, your claim that only extreme heat can release impurities is a bit misrepresented. Here's a more accurate statement:
"A final myth about carbon is that you can recharge it yourself in a domestic oven, allowing it to be reused. To purge carbon of impurities requires temperatures of more than 1000oC (over 1800oF) at a specific pressure - in other words, don't waste your time or your fuel bill trying to do it in a domestic oven!".
Using activated carbon (charcoal) in the aquarium
Now for a clarified statement of what can cause carbon to release impurities back into the water column. The possibility of it happening is quiet extreme and I agree with you that the myth of carbon expelling impurities back into the water column needs to be corrected. Here's a scenario that could (in the extreme) cause it:
"We are often told that exhausted activated carbon will leach adsorbed substance back into the aquarium and cause problems. To avoid this, we are told to replace old activated carbon monthly. This assumption is actually wrong. De-adsroption can only be done by switching from one pH extreme (very acidic or basic) to the other pH extreme. These extreme pH values are way outside the normal range of aquarium so don’t worry about de-adsorption."
Here are a couple notable issues where using carbon can cause extremely negative side affects:
"Phosphate In Activated Carbon...can leach phosphate into the aquarium water." When using carbon, be sure it's labeled “phosphate-free”.
"A big problem with Activated Carbon is that it also removes some of the good things such as trace elements."
The most important info I found is what carbon can and cannot remove from aquarium water. Here's a short list and the link below (covering the info above too) has a very detailed list worth reviewing.
Excellent removal includes Bleach, Chlorine and DOC
, whereas one huge negative using carbon is that it can remove Oxygen. It can remove at a fair rate, Chloramine and Tannins, on the negative side it removes Potassium Permanganate. Poor or no absorption includes Ammonia, Nitrates, Nitrites and Phosphates.
Activated Carbon In Aquarium | Aquariums Life
In conclusion, using carbon will continue to be the personal choice for each aquarist as it always has been and hopefully a little clarity has been brought to the use of carbon.