Filtration, Phosphate/Nitrate levels and Algae Eaters

Subject: About filtration

> The topic of removing a filter is very interesting. The removing
> floating detrius and water circulation is what is meant by mecan
> filtration, no? But isn't it true that the nitrifying bacteria l
> filter and on the sides of the tank and in the gravel -- actuall
> the surfaces? In other words, biological filtration takes place 
> degree no matter what.

That is true.

> I'm interested in the idea of minimal filtration. What kind of f
> system would be recommended by those who propose minimal filtrat
> 20 gallon tank at work I have an Aquaclear 150 filter. The spong
> catches dirt in the water but also acts as a biological filter b
> home to the bacteria. What could one replace it with?

As long as the tank is heavily planted, and _not_ heavily stocked, 
and is fed lightly, you can probably just pull the filter out 
completely.  If you feel the need for some water circulation (some 
plants definitely do better in moving water) you can drop in a 
small powerhead.


 Subject: Desired levels of various elements
> I'm having a problem with high levels of phosphates in all my ta
> 50gal chiclid tank which has no plants, also has elevated levels
> Phosphates combined with nitrates...guess what. Yep I've got an 
> It's diatoms specifically. brownish red dusting all over the gla
> gravel, etc.. Low lighting may also be playing a part in it, but
> is in excess of 10ppm and the nitrate is around 35ppm. Prior to 
> recently did a delicate all day shifting of the entire contents 
> fish, gravel, etc., to a new 50gal tank and hood. I'm thinking t
> had to add a lot more fresh water than I would have during a reg
> change, plus adding more new gravel to the old, perhaps the bact
> were more severely smitten than I figured they'd be, and now I'm
> spikes on these elements a little like cycling all over again.

The buildup of nitrate and phospahte is _not_ from cycling a new 
tank.  They build up in any tank where there is more put into the 
system via fish waste, feeding, etc. than can be removed either by 
water changes or plants.  You will ammonia and then nitrite spikes 
in a cycling tank... when these levels fall and nitrAte appears, 
the tank is full cycled. (note: the cycle is much diminished, if 
noticeable at all, in a fully planted tank)
> Here's the question that qualifies this message in the plants ma
> exactly are the optimum levels desired in planted tanks for phos
> and iron? Recall that I'm having phosphate levels in my 75g and 
> tanks as well. The books I have and the test kit instructions do
> say for example, phosphate level should be 0ppm or 5ppm. Same th
> iron. I'm pretty sure nitrates should be kept as close to 0 as p
> I don't think you want 0 phosphates as plants need a small amoun
> photosynthesis don't they? If they get too much then they become
> algae grows better right? I have a lot of algae right now, and I
> had phosphates til I got the test kit today.

Both phosphorus and nitrogen are absolutely essential for the 
growth of plants.  But they are needed in much smaller amounts 
than are usually present in a "fish" tank... certainly less than 
you have in yours.  I prefer to keep nitrate below 10ppm (below 
5ppm is better) and phosphate below 1ppm (I'm happiest if the 
level is unmeasureable)  IMO< as long as any iron is measureable 
in the water, you probably have enough, or the plants would have 
already pulled it out of the water.

Subject: Specific algae eaters for Diatom algae?

> Does anyone know if there is a specific algae eater that is note
> actively preferring diatom algae as part of it's staple diet? I'
> correcting some water imbalances in one of my tanks that have ke
> plagued with diatom algae for a long time, but I was thinking of
> an algae eater to this tank anyway, so I figure I might as well 
> one that will find the smaller remainig amounts of this stuff ap
> Thanks

Yup.  Otocinclus will polish off amazing amounts of diatoms... Six 
of them _completely_ cleared out a 55G tank in one weekend a while 


Karen Randall
Aquatic Gardeners Assoc.
Boston, MA