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Balancing new and old tanks
Something which I didn't mention (but which you maybe infered)
in my previous message was that the 49g tank with the hellgae
in it was an established tank for quite a while. This is quite
different than taking a fresh tank and populating it with
rather clean gravel & perhaps laterite, vermiculite and some
nice mud and starting from fairly sterile conditions. The
problem with an established tank is that there is already a
lot of algae growing in it even if it seems not to have a
problem. 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.
To return to my point, when you increase the light levels in
a tank that has a stable equilibrium like that and throw in
plants, usually what happens is the algae reproduces very
quickly and can interfere with the ability of many plants
to perform photosynthesis. 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.
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. We can get
back in balance even in a tank with lots of organics and
feces because the plants can be pretty adept at drawing
nutrients from the substrate (esp. with clay or mud additives
to help fix cations and encourage root hair growth). That also
helps them keep ahead in the growth game. This gets us into
the maintenance phase where we have to remove the older leaves
which start to look ratty, die back and collect 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.
Bump the lighting up even stronger and the algae comes back
with a vengeance again. Maybe we've got to take stronger steps.
The plants which grow slow and don't have some kind of a natural
defence which prevents algae from growing on them have to be
shaded. We've got to ensure adequate CO2 and nutrients to
kick the plants into high gear. 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. Another thought is going to the
trouble of adding a micron level diatom type filter into the
system to run on a more or less continuous basis. The idea would
be to remove as many of those algae spores as possible from the
water. At least on a temporary basis that probably makes a lot
of sense as an algae treatment measure even if the algae is not
a green suspended algal bloom. 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?
Another strategy is to start with a sterile tank and introduce
only a few fish at a time starting with algae eaters. Don't
introduce algae and you've gone a long way towards what takes
you weeks and months to achieve by diligently cleaning the tank
and ruthlessly removing algae affected leaves and plants. The
5% bleach treatment is also pretty good at removing the algae
that comes from the store leaving the air born spores esp. the
blue-green algaes. I think these are the ones found commonly
in the air, true? If you have a tank without brush algae and
you don't introduce it, can it arrive by airborne spores or
fish? Heck of a lot better starting off without it.
I might even resort to this drastic step if only as an excuse
to redo my substrate with a Kelly style mix. Either that or
forget about growing plants and just focus in on the algae. ;-)
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... ;-)
Steve