i was just going through the threads for PMDD and came across with this one...the above person says that phosphate was used as a limiting factor to control algae growth, i've read that phosphates are not added as it is naturally added with fish foods n fish poop which seems to be enough.
not trying to contradict but this is wot i have come across as even i'm doing a bit of research for plant fertz for my planted tank..
Well, at non CO2 levels, the demand is about 10-20X less than a higher light CO2 enriched tank, CO2 alone will increase growth 10X.
10X more NH4 is not a good idea, that's why folks add KH2PO4, KNO3, Fe etc to such tanks.
If you factor the RATES of GROWTH in, then the different methods make a lot more sense as to why and how they work. Clearly, 10X less growth is a trade off for one method vs another.
In a lower light tank, adding PO4 may not be
required, your tap might have some as well, but adding more clearly does not induce agae in both a CO2 enriched high light tank nor a low light non CO2 tank either, which tends to be a more NO3 limited system and PO4 can build up somewhat.
You can add NO3 and PO4 etc to a non CO2 tank and not induce algae as well if the non CO2 tank is fully planted and stable.
So excess levels of PO4, NO3 etc are not the cause for algae.
Algae are clearly not limited by PO4 when you add 2-3ppm per week.
Would you or anyone argue differently?
I do not see how.
I was the one that disproved the hypothesis of PMDD, however, by adding PO4, the rest of the nutrients in PMDD took care of the plant's needs.
So the entire method just needed that one tweaking really.That was about 10 years ago when I started in on it. I'd been doing it for several years before hand though.
PMDD did supply all the other nutrients to the plants in otherwords.
The problem with the theory and most that suggest X causes algae: folks do not bother to test their supposed "causes" well.
They give advice based on correlation, not cause.
They rarely test their fears as well.
You cannot suggest to test with a kit on one hand and then not test your own advice on the other.
You make the hypothesis, you should bother enough to at leats test it.
That was not done. The rest of the work was good though for plants.
All you need to do to test a hypothesis: set up a test that can disprove it(a defining factor of any testable hypothesis).
So all I needed to do was take a tank full of plants, running well, non limiting light/CO2/all the other nutrients, stable tank etc, dose PO4 to .5, to 1.0, to 2.0, etc and observe and wait for my algae.
I've been waiting about 15 years and Still, no algae.
If this hypothesis where true, I would have to see algae blooms, but I've not under an extremely wide range of conditions, time frames, etc.
So I have to reject such a hypothesis.
It cannot possibly be true.
There is strong support from Bachmann et al 2004 in the research for ntural shallow warm water lakes in Florida with high plant biomass. Adding PO4 will just = more aquatic weeds, not algae.
Most aquarium fertilizer companies sadd PO4 to their ferts as a result these days. 1000's folks add KH2PO4.
Plants define the system, not the nutrients is another way to think about it.
Note, simply disproving the hypothesis behind PMDD did not prove what caused algae, only what it could not be causing algae.
That's another question and I proposed an answer and have a fairly good model that seems to work. At least until I or someone else can disprove it, but no one has and it induces algae very consistently.
Regards,
Tom Barr
www.BarrReport.com
