Activated Carbon...

[DubbieBoy]

A quickie,

Does activated carbon filtration remove plant fertilisers and trace elements from the water in the same way that it removes meds ?

Cheers.

[Matt]

Yes it does, you don't need carbon with planted tanks as healthy plants with remove impurities from the water by themselves.

From http://www.fnzas.org.nz/filtration-3.0.html

Types of Media

Activated Carbon

The most familiar chemical adsorbent is activated carbon. Activated carbon should be a little larger than pinhead in size. When washed and dry, it should be dull and not shiny. When placed in water, it should hiss. It should also tend to float at first. Be careful of charcoal, however, because it is dull and floats, but does not hiss. Charcoal is usually very soft, crumbling easily between the fingers and is usually available only in pea-size. Good activated carbon is hard but fragile, feels hard and does not crumble, but fractures under finger pressure. Not all true activated carbons are equivalent. The most common available carbons are economical water purification grades, usually derived from wood or nutshells. These are not bad carbons, but you may wish to seek out some better grades. The best carbons are usually produced from bituminous coal and have high porosity and low density. They should also have low ash content to minimize impact on pH. Most activated carbons need to be thoroughly washed prior to use. Because it is soft it has a tendency to crush a little during shipping and is therefore covered it carbon dust. Rinse in clean befor use. All activated carbons release phosphate, despite claims to the contrary, and only those that release the least should be selected for reef aquaria.

Activated carbon adsorbs a small quantity of ammonia, nitrite and nitrate, but the quantity is quite small. In most aquariums it would take a large bucket of activated carbon to remove enough nitrate to be effective. Its main use is to adsorb organic compounds. These compounds give the water its aged look (yellow). It adsorbs dissolved food, fat, and minute dirt particles.

Advantages: Easy to use, Relatively Cheap, quickly polishes the aquarium water.

Disadvantages: Must be cleaned before use, has a short life (approx. 1 month), many carbons tend to release the waste products back into the water once saturated, does not specifically target unwanted compounds (often removes fertilisers from planted tanks), releases phosphates into the tanks water when first introduced.

[DubbieBoy]

Thanks for that; I was just curious.

I don't use it continuously but rather for an occasional water 'polish', leaving it in for just a few days. It really makes the water crystal clear.

Looks like I'd be wasting my time adding fertiliser while its in there though.

[Warren]

If you find the need to polish the water you can use Seachem's Purigen instead of activated carbon. It's not cheap to buy but unlike activated carbon, Purigen can be easily regenerated for many uses. Mine is 5 years old and Ive regenerated it at least 50 times.

It seems to leave all the trace elements alone and keeps the tank looking really white and polished. It will cost about 5x the price of activated carbon but considering the number of regens, it works out overall at 1/10th the price long term.

Instead of using Prime as Seachem recommends to neutralise the chlorine from the regen process, you need only add about 1/2 a teaspoon of sodium thiosulphate crystals to the equivalent amount of water to get the same result. It is much cheaper than using Prime.

[Ira]

Not that easy to get access to sodium thiosulphate...Although, Prime isn't easy to find either, I've never seen it for sale I don't think.

[Warren]

Sodium thiosulphate is easy to get. I've got 25kg's sitting in my shed. It's available from most industrial chemical suppliers.

Prime is available from Hollywoods. They take credit card orders over the phone and will courier no worries. Your LFS will have access to it as well but they will have to order it in specially.

[Vjarn]

how do you regenerate prime?

[Warren]

You don't. Prime kills the chlorine used to regenerate Purigen. It is a one way chemical reaction. Once prime is used to kill the chlorine you throw it out...