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Re: Chemical Filtration

On 6/3/97 Mark Shelton <mark_shelton at pobox_tbe.com> wrote:

>Subject: Chemical Filtration
>     Like most people (I think) on this list, I do not use any form of
>chemical filtration (e.g., carbon, etc.) for fear of plant nutrient loss.
>Between weekly or biweekly water changes, the water becomes noticeably
>yellowish and dingy as expected without the carbon. I would certainly like to
>use a filtration media that would yield a continuously colorless water. 
>So, is
>anyone using carbon, perhaps in small amounts, in their plant tanks without
>causing significant nutrient deficiency ? If not, are there any other 
>media that can be used successfully (e.g., Purigen, Renew, etc.) that are 
>absorption/adsorption selective ?


What I've done for yellowing a couple of times is to steal a trick which 
Julian Sprung recommends for removing colouring from water in reef tanks 
and just drop a bag of carbon into the back of the tank. Don't place it 
into a filter, and don't force water through it, but just place it where 
you get good water flow over it. Julian Sprung recommends sump placement 
for reef tanks, and notes that it does not seem to cause significant 
nutrient loss in reef tanks. I've done the same thing with both carbon 
and the small bags of Purigen and it's quite effective. Purigen 
discoloured quite slowly and lasted quite a long time between 

This technique removes the yellowing quite well and doesn't seem to 
interfere with anything else. You should notice significant results 
within 24 hours. It's also cheap since the media lasts longer since it's 
not being used as heavily as it would be if you were constantly forcing 
water through it. If it does remove any nutrients, it will probably 
remove much less than would be removed if you actually forced the water 
through the media.

I haven't had to do this recently, however, since my water has remained 
extremely clear since I increased my planting level some months ago, and 
removed my sole piece of wood. I think that the standard recommended 
"heavily  planted tank" clears the water on its own quite well, but that 
may not be the case if you have wood in the tank since that seems to add 
a lot of yellowing from the humic acid it leaches. A high fish 
load/feeding schedule can also result in a high level of organic wastes 
and some colouring of the water.

David Aiken