Friday, February 14, 2014

Plants and rotting tubers or rhizomes in the BCB...what to do?

Hi Kevin,


Last month I tried to plant my new Biocenosis baskets with plants (tuber type), yesterday I opened one of the baskets to see the roots development. Very nice! BUT, some of the older part of the tube were rotten and smelled bad.


My question:

1. Assuming the other planted baskets also have some part of the root rotten, do I need to open all the remaining baskets, clean the roots and re-plant them?


2. The bad smell meant there were some anaerobic bacteria present right? In this condition, will the bad anaerobic bacteria take over the biocenosis basket? Or even worse, take over the other (unplanted and already matured) baskets in the AFS chamber :(


Your view is greatly appreciated, as usual....





Hello Dipa,

Sorry about the long time no reply but emails have been demanding. The plant tubers or a rhizome you talk about turning black is normal. As the plant gets older the new growth and roots are at one end and the old root of the plant that is not needed any longer is now dyeing.  It’s like the old wood on bushes that has to be cutout so new growth can takeover. This is one reason that in the emergent zone of natural ponds it’s an always changing and spreading zone. But you probably already know that.

You do not have to replant any of the BCB’s before their time when plants that have tubers are present. The blackening of the substrate is normal with tubers and rhizomes so there is nothing you can do about it. It’s not the media that is going bad but the tuber itself is now beginning to rot from the inside out and being attacked by anaerobic bacteria which is the natural order of things. When this happens to me I just discard the small section of black cat clay- it turns black because of the rotting tuber not from the bacteria in the clay itself- in that section only and keep the rest if it looks good still. It will do no harm to your plants or fish because of its containment and facultative bacterial competition for oxygen and space is utilizing all ammonia that is being produced from the rotting tuber. Because of this bacterial competition, things inside the BCB stay in an anoxic state always and the BCB does no go anaerobic. Healthy BCB’ will always stay that way if plants are left out of the substrate, but then the filter would have a sterialized look to it  if it were void of at least some plants and not be very eye appealing to onlookers.

Now if you were like some hobbyist and plant your plants into the ponds substrate of rocks and gravel like they do here in the USA like Aquascape’s hobbyists do and bog filters, then the bacteria competition would not be present since the intersection of topography is gone because of the liner that we use and chemical and biological pathway are blocked.  The tubers would then begin to rot as always but because of the lack and/or absence of oxygen I should say, only anaerobic bacteria would dominate the area were the tuber is.  Ammonia (NH3) instead of being utilized by bacteria and the plant would go back into solution once again. This never ending cycle only does more harm than good in an enclosed system like our ponds if water is not being exchanged every day.  I show photos in my blog of such blackening of stones and liners from hydrogen Sulfide gases/acid. The plant also becomes smaller and smaller with each passing year because the tuber is exhausted and if not given more fertilizer in the form of tabs, it will perish leaving that rotting tuber behind. As the tuber becomes older the bacteria will begin turning it into mush/coosh by breaking down the proteins and it then becomes another organic in the nitrogen cycle of the pond. Like we really need more of what we are trying to have less of!

Plants grow best in anoxic conditions and not at all in anaerobic conditions. That is why plants in the BCB’ grow so luxuriantly in a BCB and can outgrow their baskets in just one or two seasons without fertilizer additives.  Laterite, ammonia and low but not absent of all oxygen is the trick to healthy plants.





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