Charcoal and planted tanks... need your feedback

[AthagaMor]

The article (http://aquaticconcepts.thekrib.com/Seminar/Basics.htm)


Slide 38 What about the ever-popular chemical filtration products that seem to take up half the shelf space in a typical fish shop? Fuhgettaboutit! Plants will provide all the chemical filtration you need and, more than likely, the chemical filtration products will just wreak havoc with your water chemistry and fertilizers! A good planted tank has:

No activated carbon (charcoal) - it will remove trace elements!
No resins or chemical pads - they also remove trace elements
No UV sterilizers - they oxidize iron
No phosphate buffers - they will cause algae
Be careful of water conditioners - some will remove heavy metals (AKA trace elements!)

Above is an article and the quote (more specifically the bold) from the article I'm concerned with. Having read the whole of the article closely, I got the impression the author knows his stuff.

I currently have driftwood (walabi and grapevine) dumping large amounts of Tannin into my water and I was told that using charcoal will take the Tannin out. I also have a moderate number of plants in the tank and plan on getting more. The charcoal is in a power filter. Should I just take out the charcoal and/or replace it with <insert something> (sponge maybe)? Someone suggested boiling the wood to stop the tannin bleaching... I guess I'm dealing with two issues 1)tannin 2)charcoal.

what would you do?

[promethean_sprk]

The tannin probably lowers your ph, which is probably good. The only problem is the staining of the water, but that should fade as the wood ages. I've used activated carbon and didn't really notice anything wrong. I think there was enough trace elements in the substrate to support the plants.

[RTR]

Activated carbon will remove tiny amounts of trace elements, especially the chelated ones. But this is not a big deal. The amount removed is tiny, and will be a fraction of the routine dose if you are using a trace element supplement such as Seachem's Flourish or other comparable brand. The adsorbtion is specific to the particular element or chelator, and then the sites are saturated, so unless you are changing your carbon out every 2-3 days, you would be unable to detect the differences in water column levels, even if you had tests for the particular elements. In other words, it has basis in fact, but as commonly seen on the boards is another aquarium myth. Your plants are unlikely to suffer due to the pesence of carbon as ordinarily used.

Re the tannins, boiling is a big help IME, but better with regular sand-blasted driftwood than with Mopani or other immediately-sinking bogwoods. The latter seems to me to have particularly lasting seepage of tanins. I do boil it normally (in an old enameled crab pot when my wife is not at home); then it still tints the water for an extended period, but a very pale tint, so more easily pulled with normal carbon usage.

Regular driftwood gives up a good amount of its tannins with just my usual pre-soak until it sinks; very little after a boiling session following that presoak.

HTH

[Mark_b]

That whole thing about the oxidisation of iron by uv sterilisers is a bit dubious.
It takes a large dose of uv to do anything to the chelated iron in the water, such a dose is not going to be provided unless you have a very high power bulb in your sterliser ( > 25w ) and your flow rate is very slow through the fitting.
Im afraid i dont know about the charcoal but just thought i would say that if the info is wrong about the uv then maybe it is about the charcoal too!?

[AthagaMor]

awesome, thanks for the replies, All. I don't hold the article as the "be all, end all" - its just the best all-in-one-spot source I could find. I'll ignore the UV info in the article then (haven't gotten to that point yet either *wink*). Thanks!

I've done one water change and plan to do another when I get home. Seems to be helping. I don't mind the amber color - it was just starting to get dark.

From what RTR described, I've got one piece of bog-wood and one piece of regular driftwood (since I put a large rock on it to keep it down.

[HazyWater]

Light about 520 nm and shorter can oxidize the dissolved organic chelator of iron. This releases Fe2+ and makes it available in the water to both plants and algae. Its called photoreduction of iron.

Having algae problems? Block the blue spectrum of light to help tighten the noose on your algae. Also, fresh activated carbon will remove the chelators and any iron attached to them. Its a good thing to remember.

[beviking]

Hey wait a minute. What about the "Be careful of water conditioners - some will remove heavy metals (AKA trace elements!)" part? Don't the conditioners just "detoxify" the metals? Not remove them. Does this make those elements inaccessable to plants then?

[promethean_sprk]

If the high frequency light makes iron available to plants, wouldn't a UV/blue lamp shining on the bottom of the tank make iron available at the bottom of the substrate? Most stands you could put a lamp under them...