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Re: PO4 heresy
>Steve Dixon wrote:
>> Many of us strive to maintain phosphate-limited conditions in our
>> planted aquaria. This is one of our basic algae control strategies. Can
>> there be such a thing as having too little phosphate?
I agree with this notion.
>Steve and I are members of the same local aquatic plant group in San
>Francisco, as are Tom Barr and Dave Gomberg. About 1-1/2 months ago I was
>complaining to each of these experts separately about my strange staghorn
>algae, slow plant growth, etc. Dave pointed to PO4 as the limiting factor
>right off but I dismissed this idea - I couldn't believe that adding
>phosphate could possibly make an improvement. After all, I'd spent months
>learning how to limit my tank with it, and seen the improvements from such a
>I had been maintaining near-ideal conditions for a long time in my CO2
>injected 50g (110w PC fluorecents): 6.6pH 4.0dKH, 6.0dGH, trace ("some")
>Fe, 10ppm NO3, and I feed my moderate-to-heavy fishload sparingly.
Rather than add more NO3 and P why not add more food? Over fed if needed.
Using Flourite you also have less need for the Fe. Also..... don't you add
jobes to the gravel also? The palm ones?
>watching all of the macro-nutrients individually and together, and was using
>TMG and Seachem Equilibrium regularly. I couldn't figure out why the tank
>wasn't taking off, especially since it had really been going great-guns for
>about two months. That was the clue, and I missed it.
There are other things it could be too .......
>> I'm using 1/10 gram amounts of potassium monobasic phosphate with
>> quite surprising results (beautiful, is actually the right word for it)
>> variety of high growth conditions. I have a fairly good feel for what
>> supplement is doing to nitrate levels (driving them down, as one would
>I borrowed a lifetime supply (thimblefull) of the stuff from Steve about a
>month ago and started experimenting, watching NO3 and PO4 levels carefully
>with Lamotte test kits. It turns out that with my plants, fishload and
>feeding schedule I can use about 1/8 gram PO4 and 1/4 tsp (haven't weighed
>it) KNO3 every two to three days. That proportion is critical. Too much
>PO4 and I see GSA and BBA, too little and growth stops almost immediately
>and staghorn algae takes over. I should point out that algae intrusion is
>dramatic in those cases, literally taking over the tank in a single 10-hour
So you have to test for yet another element to use this system(PO4 and NO3)?
I know for a fact I have run some PO4 deficient tanks and I know what they
Algae ain't a sign of it BTW!!! Certainly not BBA nor GSA. I have run some
tanks using PO4 remover trying to rule out a P deficiency for red color
intensity. Growth and color were not as good in this experiment. No algae
though....................not very bad growth but slower growth and less red
More classic purple color out of Gymnocornis sp. But the cause of your algae
is not due exclusively to the PO4 being limited. It is balance and
biological in nature.
I agree that plants need some PO4 though.......enough to crash your tank or
cause algae? Not IMO.
The Theory of PO4 limited tank is still a good one IMO. Some plants may have
a problem with little PO4 in there as there are exceptions with all the
different weeds we grow.
>Plant growth has been phenomenal lately. I live with the remnants of a few
>crashes - GSA that won't go leave the rocks and Anubias leaves (but is not
>encroaching - even my glass remains clearer than it used to), dying BBA on
>my driftwood, and hair algae on my substrate (time to get some live-bearers
>- - I can't figure out why my C. japonica don't eat it).
The shrimp won't eat it. Rosey barbs take good care of it.
How long has your tank been being kept up on after the crash? If you say
about a month or a little more then..................maybe it is not due to
the PO4 your adding. There is also the "starved effect". You will drink more
water after walking through the desert for a few day with none than you
might today for example. Same goes for a plant. They haven't had any Fe or
PO4 for several days/weeks then adding a good amount sends the plants into
overdrive for a few days or weeks even. Sometimes algae too if not done
precisely. This can seen with adding a jobes stick which you also add right?
If you have those in there you shouldn't have a PO4 limited tank. Add the
15/15/15 or what ever to see. Water supply (tap) might be it too. If there's
some in there or a lack of it maybe........
I use both some times(the palm and the regular 15/15/15). You can add the
PO4 in the form you described but I think the bacteria will cycle it into
your tank for the plants eventual use just as well and perhaps better than
adding it to the water column in an inorganic form. You risk algae more
using the water column method perhaps............... but we also use to say
this about NO3 and Diana W's book used Fe as the limiting element in the
column etc as the cause.
Again, BALANCE, is the key.
Another thing is when we are having a problem we often try to keep up on
everything very well.
When we aren't, we don't. I've crashed so many tanks I suppose I could be
the crash test dummy.
I know this issue of crashing all too well.
Steve's coming over this weekend with his "secret" so I will try it on my
test tank at extremely high light and let folks know what happened. It is
worth looking into IMO. Even if you don't believe it!
Such Heresy! But he may be on to something too.........there are many things
that I did (and still do)that were heresy(and still are to some) at one
point also. I think his notions have really furthered the plant tank cause.
He is good at "tweaking" the tank. I could be wrong ..............but I have
to try it myself. PO4 has never been an issue really for any of my tanks
ever. Adding it won't hurt too much I believe either. I've added some high
PO4 fertilizers with no negative effects to the column.
> I'll let you all in on a little bit of heresy I've been experimenting with
> recently. Many of us strive to maintain phosphate-limited conditions in our
> planted aquaria. This is one of our basic algae control strategies. But
> what do we really mean by that phrase? Can there be such a thing as having
> too little phosphate?
I agree with this notion. I have added it (PO4) in the form of jobes sticks
with good results and from good feedings, not little or sparingly amounts of
food. The food method worked best IMO.
Other folks have fed the tank with fish food also with great results. After
the water is changed also........and I have used PO4 remover with negative
results growing plants both with color and growth rate.
>mrubin at visa_com