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Re: Klaus's tank

>Hello All,
>my problem is the high NO3 in my tank, actually 25 to 30 mg/l, and I see no
>chance in the moment, to reduce it. The reason for high NO3 is probably to
>many fishes, and I will not kill some of them. A thumb rule say, 1cm fish
>for 2 liter water, my ratio ist about 1 cm fish for 1.1 liter water. I will
>try to reduce NO3 by
>1.) special type of biologic filter, so called "slow throughput filters"
>(stf), or (and)

These are very good actually. Try combining them with a plant filter.

>2.) a plant filter.
>To 1.)
>Stf are distinguished, in opposite to "high throughput filters"(htf), by an
>extrem low water flow and a big volume. The low water flow through the
>filter causes a defizit of oxygen in it and therefor the process of
>denitrification will start, 

This can be done both in your substrate ( a good reason for deep substrates)
and in the nature of certain types of media. But do you want to grow
bacteria to control your NO3 or plants? I think over all the plants are
pretty tough but they need some other nutrients besides the NO3 unlike many
bacteria which can be very specific to the types of nutrients needed. You
need to figure out if this is something you want or need to do. Bacteria are
nice and needed but I personally would rather look at plants. 

if the oxygen is low enough. My tank has a
>capacity of 200 liters. Has somebody experience with construction of stf
>(volume in ratio to tankvolume, rate of flow, material inside the filter,
>type of low flow pump a.s.o.) and of course praxis experience? In any case I
>would run my htf in the first time parallel to the ltf.

For a 55 gallon tank or 200 liter tank, about 20-35(75-135 liters) gallons
an hour for the stf.
Volume....about 2-3 gallons(liters 7-12), material........spiorex, fluval
ceramic rings, matrix by Sea Chem, crushed lava, Tunze granovit(? I forgot
the name), hydroponics clay media, anything with lots of surface area and
internal area. A small Rio/Maxi jet/Otto etc will do nicely. I would use a
valve to slow the flow down for this filter. 

Another idea is to batch control your filter. It's based on an overflow
system and a timer-power head pump. Every hour it processes a "batch". A
small sump for the batch is placed below your tank. A small pump empties the
contents  to the main tank and the resulting overflow fills up the sump
reservoir again ready for another "batch". This batch can be processed for
however long you wish by using a timer attached to the pump. A similar
method can be done with a plant filter and a sump for zero NO3 returns of
effluent. I think you just want to lower it (NO3) right? Adding a tube of
PVC or deleting one can give you the control your after. I think the best
idea is for a plant filter.

Plant filter.......about 100-200 gallons(liters 380-760 total) hour to get a
nice result. Hydroponic clay ball media, Volume....... the more the  better
depending on your fish loads/feedings.   A few(say 4 or so) PVC tubes 3"
inch X 12" long (8 dia x 30cm) with a plant in each should do fine. A small
pump like the others would do fine left on full flow. A 100 liter /hr flow
to each should do well. Tunze should still have them over in Germany or you
can easily build one for much less $.  

>To 2.)
>Alternativ or in addition I will establish a plant filter. One year ago, I
>did already so, and I measured NO3 and made a diagram. I got a reduction of
>NO3 some weeks after starting the filter and an increase of NO3 again some
>weeks after removing the plant filter. As plant I used the airrootes of
>philodendron. As far so good. My concern is, that the plantroots will not
>only "eat" NO3, but also the furtilizer, 

Yes they will do this! But it is the price you pay for plants and too many

I put into the water, and which is
>foreseen for the Tankplants. Do you have concrete knowledge about this

The submersed plants will shows sign of problems first. The plants in the
filter are about 5 x times more able to use the NO3. By testing your NO3 and
Fe you should be able to balance things out very well. Later you'll get an
"eye" for it and not have to test much at all. Spathiphyllum sp are good, as
are most tropical houseplants. Spath's are fast growers, cheap and need
little light so they are good.

 Is it necessary in this case, to increase the amount of furtilizer,
>getting shure, the waterplants have enough?

Say if you use Tropica Master Grow, test your Fe to see if there enough for
your submersed plants. 

> Klaus Haber, Ingolstadt, Germany.

Tom Barr