Originally Posted by iceprizm
i would like to know the answer to this as well. I would rather have some biological in a canister, just in case. I dont stock heavily and would rather be on the safe side.
Byron: in your planted tanks do you use any biogical media in you filters?
My previous post answered the original question, so I'll respond to your subsequent questions here.
If you stock lightly there is even less need for filtration in a planted tank. I stock heavily, at least I think so, and have not encountered any problems that I can discern in 15 years. As I've written elsewhere, I've used this approach to tanks long before I ever knew the reasons it worked.
I have one canister on each large tank. They are Eheims on two and Rena ZP3 on one, so basically the same type of filters. In the first basket I have ceramic disks, in the second I use Fluval's Bio Max, and then there are the pads. Obviously all media acts as a biological filter, just as the plant leaves, tank walls, wood and rocks--any surface under water that is in contact with moving water bringing oxygen will support a colony of bacteria.
My initial point was that you not add "extra" biological filtration because in my opinion based upon my research and experience it is completely unnecessary for the fish, and possibly detrimental to the plants. We all know that one can have well-balanced and very healthy planted aquaria with no filter (by which I mean equipment) at all. For more than a hundred years this worked. The fish stock has to be balanced with the plants. I have more fish than the natural balance, so I use a canister to circulate the water and as "insurance" I suppose.
Another example of how this works is in a new tank. If the new tank is well planted, you can add a considerable load of fish on the first day and there will be no cycling issues whatsoever. The plants use the ammonia/ammonium before the nitrosomonas bacteria even have the time to become established. If this wasn't the case, the fish would be dead. And while I do not normally "push my luck" by doing this [I don't overload new tanks for a few days], once back in 1997 I had reason to do this.
The fish in my 115g were very lethargic and I had been losing fish regularly over a period of weeks and could not discern the cause. It turned out to be a case of some (unknown) toxic substance in one (or perhaps more) of the large chunks of wood in the tank. Anyway, I had to disinfect the tank completely to remove all trace of the toxin. In one day, I tore the tank down and re-set it. The 125+ fish were moved into my spare 33g, the filter was cleaned and all new media inserted, the gravel was thoroughly washed bucket by bucket in hot water and replaced, the plants were washed in warm water as best as I could, all wood was removed, and the lace rocks were scrubbed with a brush in a sink of very hot water. Everything (except no wood) was put back, tank filled, NovAqua added to de-clorinate, and all 125+ fish netted back, all within 12 hours. The only bacteria that could possibly have survived would be whatever was on the plant leaves that I didn't wash off. I had zero ammonia and nitrite and not one fish loss or even a sign of stress aside from the ordeal they had gone through. If the plants didn't use all that ammonia I certainly don't know what did.