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>> You mention having spot algae with 5 - 10 ppm nitrates and 0 ppm PO4.
>> Several of us here on the West Coast have observed that well-run high light,
>> CO2 supplemented tanks often show a very noticeable benefit from the
>> addition of small amounts (under 1 ppm) PO4. This can on occasion include
>> reduction of spot and other types of algae as well (anecdotal observations
> I have a weak solution of potassium phosphate monobasic, and I
> usually dose about 0.050ppm every two weeks or so. I was scared
> to use it more often or to use more, since I already had some spot
> algae. I thought it would only increase the algae population. More
> nutrients=more algae. I guess it couldn't hurt to try. I'll observe any
> changes over the next few weeks and report back and findings:
> good (hopefully) or bad. I keep K levels around 20-30ppm, so PO4
> is all I'm lacking. Honestly speaking Steve, this is my only PO4-
> limited aquarium. EVER! I've always fought to keep PO4 levels
> down, I've done it for years and years. Adding PO4 now is like
> sticking my hand in the fire. It just doesn't feel right ;-)...
I too was leary to add PO4 to my tank, but from reading past posts to
the APD couldn't help but conclude that my 100 gallon tank was severely
phosphate limited. I thought that the relatively heavily stocked tank would
be getting enough PO4 from feeding the fish, but the tank is also heavily
planted, and this turned out not to be the case.
Just as a base for comparisson, my 100 gallon has 256 watts of T8
fluorescents (8 tubes backed by a rather ineffecient reflector), 1 bubble of
CO2 every 2 seconds and 3ml PMDD with 2X KNO3 and .06ppm of PO4 dosed to the
water column daily. I change 25% of the water every week with a 50/50 mix of
well and R/O water that blends to 6 degrees kH. Nutrient levels in the tank
stay around 5ppm for nitrates, less than .1ppm iron, and the PO4 from the
previous evening is gone each night an hour or so before lights out when I
I snuck up on this level of PO4, starting with .02ppm every other day
and working up to where I am at now. The PO4 is still used up every day, and
the plants are growing and looking much better.
When I hear of other people going to all kinds of trouble to remove PO4,
I almost feel guilty to be adding it, but it's working for me. Perhaps if I
filled the tank up with discus.....
see my 100 gallon at