RE: [APD] Nutrient Problems

["Eric Wahlig" <ewahlig at earthlink_net>]

Reggie writes:

"Okay, anyways about 4 months ago I switched from a DIY spiral compact
fluorescent hood to a set of AHS compact fluorescents.  The tank went
through a period of temporary upheaval, but after a couple weeks, the algae
started getting under control.  My plants were growing, but not thriving. 
My rotala magenta started growing its intense red, but after a few weeks it
was back to the less pleasing orange.  I increased my dosages of tetra's
florapride, but that didn't do the trick.  My ludwigias were also growing a
duller pink."

My thoughts on this are that you increased lighting and saw a reaction in
the tank balance but overall the plants enjoyed the change. The key here is
that you noticed a nutrient deficiency when the plants ran out of their
stored reserve as evidenced by the reds dulling.  Increasing the Florapride
had no effect so that would indicate to me that a major/macro nutrient was
in short supply. N, P, or K. I'm not sure what Flora pride has in it but I
don't think it has these macros does it?


"Wishing to see the better colors out of my red plants, I felt it would be
a good idea to add one more CF light.  I ordered the 10,000 K bulb and
bright kit from AHS and installed it once it came in.  For about 2 days
everything was looking good.  The desired plants were showing vibrant red
new growth. Then all hell broke loose."

I'll bet it did; been there, done that. The plants were basically out of
gas but the ever present algas were ready to go at a moments notice since
many of them can live on next to nothing in the way of macros and they had
plenty of micros at hand.


"I made the PMDD and supplimented it with some tetra florapride to make up
the micros.  I hesitated to add too much florapride (0-0-3) because I
didn't want to cause a potassium excess.  I have been dosing at 5 drops per
day of Conlin's newest formula (found on theKrib.com) for about a month
now."

I think you're going to need macros N, P, and, K at this light level. The
low production of N and P being produced by the relatively low number of
fish, shrimp, and other N producers. Another point I might make is that
many of your plants are relatively slow growers that prefer a lower light
level which matches their growth rate (Java moss, Madagascar lace, Anubias
nana, Bolbitis heudelotii). These plants may not be able to absorb and use
the higher levels of macros that the red stem plants and duckweed need at
this light level. With this plant selection it seems to be a very tricky
balance at this light level. The Crypt wendtii can take higher light better
than many crypts but such a sudden change probably shocked the plant and is
the primary cause of the melt down. Having an inefficient CO2 system at
this light level invites disaster. My suggestion would be to reduce the
light level to one 55w PC tube and get the tank balanced again. I see you
are testing for N and P so add these until you get a small reading of N
(~5-10 mg/L) and P (~.5-1.0 mg/L) and keep up the PMDD. When you are
confident that the tank has returned to the balanced state that you had
before then you can slowly increase the lighting, CO2, macro nutrients, and
micro nutrients together so that you keep the balance as you run the tank
faster. In the natural world, the ratio of daylight to darkness in a 24
hour period is always changing, either increasing or decreasing, but the
daily amount of change is very small. 


---Eric



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