Re:Balancing new and old tanks

>From: Stephen.Pushak at saudan_HAC.COM
>Date: Wed, 18 Oct 95 18:35:30 PDT
>Subject: Balancing new and old tanks
 A tank which has very low light, not many plants or
>plant photosynthesis surface area, lots of fish and a good
>healthy bio-filter colony has loads of nutrients both in the
>water and in the organic wastes (feces) which have accumulated
>in the gravel. Only certain plants can grow (very slowly) in
>those low light conditions.

Not true. The floating plants can grow rapidly - and some are even pleasant
to maintain, like water sprite, Ceratopteris thalicroides or C. pteroides.
In addition to getting more light at the surface, they also have the aerial
advantage to get atmospheric CO2. Any fast growing floating plant will do.
Duckweed is great if you can stand it. After a few buckfuls of floating
plants, it will be time to thin them out thoroughly and allow the light to
penetrate below again. Among stem plants, Hygrophila polysperma will do OK
in low light (1-2 w / gallon) and be some help to reduce nutrient load.
Unfortunately, it is now illegal to purchase down here. :(  

> The best plants for competing with
>algae are the ones that also grow so fast that the algae
>doesn't get thick enough quick enough to endanger the leaves.

which is true for the floating plants.

>I think what keeps those algae in check is that with enough
>plants, the aqueous concentration of nutrients gets low
>enough to restrict the growth rate of the algae.

I agree this is the primary factor, but perhaps with only one or more
limiting nutrient - like a trace element - which the plants can store. In
tank with soil or clay (incl. laterite) substrate, Fe can be kept mostly out
of the water to discourage or limit the algae. A second factor is
allelochemicals released by the plant to inhibit algae.

> With
>the stem plants, just pull them up and replant the tops. If
>the bottoms are good enough to sell, you might convince a
>local store to give you some credit towards other purchases
>for 'em.

I always cut off the tops and bring those to the store. I would never think
of selling the bottoms to the store. As a customer, would you want to buy
the bottoms? When you cut off the tops, the plant will come back quickly. I
only remove the bottoms (and throw them away) when the substrate gets too
rooty or when the bottom stems start looking trashy and full of roots with
few leaves. I always have some other bottom plants to hide the lower stemps
anyway. But, I have to admit, my tanks don't have the nice manacured look
you see in the Amano book. Too much work for me. BTW, I just got Amano's 3rd
book. Smaller, but each picture is exquisite and frameable. (The same is
true for his great calendar. )The 3rd book is more of an advertisement of
his business and includes pictures of his products, and unfortunately, the
text is almost exclusively in Japanese.

>Bump the lighting up even stronger and the algae comes back
>with a vengeance again.

This must be done in proportion to the amount and healthy state of the
vascular plants.

> We've got to ensure adequate CO2 and nutrients to
>kick the plants into high gear.

added CO2 is good for this. 

> Does this mean we'll be pulling
>plants out every second week or so? I think this is the case
>with a lot of plant types.

But may necessary, until algae is under control. I once added CO2 and
harvested plants until things were in check. Then I removed the CO2 and the
plants continued to dominate the algae.

> Another thought is to use one
>of those UV sterilizer devices. For about half the week turn it
>on and then leave it off when you add the chelated Fe mix.
>(UV breaks down the Fe pretty quickly according to other info
>posted here previously) That might be ok since the plants are
>able to store Fe for future use during times of plenty, true?

Some of the discussion on Fe suggests that Fe is stored, but not recyled
from the older leaves to the new growth. Iron deficeiency first shows up in
the new leaves. I would think that the new growth can do without iron for 3
days however. :-)

>BTW, I've noticed that certain slow growing plants don't seem
>to be bothered by brush algae eg. lobelia. Is it because the
>plant has some kind of a defence (like a waxy surface)?
>Simonized Cryptocorynes?? ahh... ;-)

I think this is true. Probably due to the allelochemicals, but conceivable
to me that it is due to the type of surface cells on the leaves which the
"roots" (holding devises) the red algae use to attach. When I had massive
amounts of Audouninella over 10 years ago, it covered the sword plant and
the Vallisneria (as seen in 4th picture (b/w) of red algae photo gallery on
AGA page), but never touched the Cryptocoryne affinis. BTW, this 1983-4
picture is same 1981-2 tank shown on AGA page and used on cover of TAG V4.
Ah, those were the days when I could grow affinis. Hmm, maybe my problem is
that I don't have any red algae. :-). 
I have to admit, it is extremely slow to load these pictures. I will have to
ask Jason to provide individual links.