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Re: low light

> Tom Barr wrote:
> "As far as PO4 from fish foods feedings, I really doubt one could build up
> anywhere near enough PO4 before their next water change to cause any problem
> provided they have CO2 even in a low light tank."
> This hasn't been my experience, at least for green spot algae, which is the
> only algae that still annoys me from time to time.

If you start with tap that has no PO4 you can see the effects of PO4 build
up and plant usage from fish feedings then add supplemental inorganic P to
make for the remainder(if you are so inclined). Fish food has other things
besides just PO4, it has lots of N (NO3/NO2/NH4). Green spot seems to appear
in tanks with higher NO3's. Drop the NO3 somewhat. If you can move the
lights away from the front glass that will help also. Also, higher trace
additions helped in a number of cases.

Having inorganic PO4 to add to a low fish load tank will elucidate this
issue. If it IS the P then you should get problems from adding the PO4 only
right? Try it to find out. Don't take my word for it. Prove it to your self.

Don't feed the fish  for awhile and add the PO4. See what your NO3 level
does. But if it's the NO3 you should have problems from adding the KNO3? Now
take this a step further and consider NH4+. It's pretty toxic but I'm going
to try this one next(after I remove everything besides the snails).
I'm expecting some algae for this addition. Not quite sure what levels are
going to cause what to happen but I have plenty of experiences with blooms
so I'll be watching. Getting a bit tried of having "nasty algae- let it go
tanks" though. The couple of "try and it and see" runs have produced some
very serious algae infestations. KNO3 is far less problematic but can get
algae presence if you push it up high enough or run at 0 too much.

I have not cleaned the glass for over a month now on the 60 gallon and it's
still very clean and clear. I keep close tabs on NO3 and P and CO2. Adding
more traces often helps green spot in CO2 enriched tanks.
Green spot is one of the "tough" algae to finish off for many folks.
The Walstaed method, non CO2, seems to have the least amounts of Green spot
IME. No iron is added to the water column. Plant growth is slower.
I'm adding iron(TMG) at 30 mls weekly total in a 60 gallon/with CO2 and
lower lighting than that method(0.9 watt/gallon).

Different systems interest me.

> The appearance of green
> spot algae on the front glass is always related to fish feeding volume, and
> the phosphate always reads higher at those times.

That doesn't mean it's P related.
What about NO3 or NH4? There's quite a bit of that in the fish foods. And if
one doses(or overdoses) KNO3 then it makes a ripe place for the green spot.
GS doesn't seem to need much NH4. Many of the other algae seem too. I;'m
sure NH4 is a trigger for many algae to start up and bloom. Could be the
case with GS but I think it's a less degree thing and not enough
traces/PO4/CO2(too little). I can sill have the low light but I can still
have good results with algae

 > Now that I am dosing N, K
> and Fe/micromix in powder form, I am finally able to have a swift direct
> affect on P measurements. The green spot is really struggling now. Which
> reinforces my assumption that high fish loads and the resultant high P level
> can be accommodated by increasing everything else, including light and CO2.

Up to a point. The higher the fish load the greater the risk at a certain
point. It's a pretty gray area due to fish load/type/feeding
schedules/forgetfulness of the owner/plant mass/light level/ and a number of
other factors. Too much NH4 production will cause big headaches if the
plants or filter(bacteria) cannot convert/use the NH4 produced fronm
fish/food waste. The more you add to a small container like our tanks the
faster this conversion needs to happen. If not, you'll get too much NH4 and
that is not good for the fish and the extra NH4 tells the algae it's time
for growth. You cannot exceed the NH4 capacity of the plant/bacterial mass
uptake or your going to let the algae get a good foothold this system. More
fish will yield more risk. If you try a bit more traces, this often helps GS
You have got all this under control though:-) Others can also.
Tom Barr