wi_blue

Why less fertilizer?
I think to help get thinks into balance. Though there are people like me that have problems with fertilizers and algae. That's why I went to the Walsted method.

Philosophos

But that's just it... Diana doesn't advocate limiting nutrients either as far as I'm aware. The issue is more one of nutrients proportionate to demands than it is of nutrient excess. Algae is far more adaptable than plants; if plants are limited by a nutrient, there is at least one algae that can easily take advantage of the situation where they can not. Rather than too much nutrients, look to too few nutrients, to little CO2, or too much light. Everything is driven by light levels when it comes to SAM's and algae.

I've got a tank sitting around that I've dosed at EI levels under low tech conditions; algae is definitely not a problem. How could this tank exist if excess nutrients cause algae?

-Philosophos

wi_blue

The thing is, in the Walsted method, that the majority of the avaliable nutrients are in the soil and there for harder for algae to access. Thats neither here nor there.... I think the idea is that the lighting in this tank maybe insufficient in comparison to the amount of ferts offered.

Philosophos

No, the idea of limiting column nutrients is your own. I have never seen a shred of evidence showing that a tank with high nutrients and yet adequate CO2 levels for the given amount of light will cause algae blooms. Diana's book doesn't agree with you either.

Check page 105 of Ecology of the Planted Aquarium and the table of critical concentrations, as well as page 78 for how it relates to the nutrients food provide. Check her statements on page 160 regarding phosphate removal and the fact that even when PO4 limitation was popular, she said it was not relevant. Go check page 164 where it clearly states that algae can take up nutrients from the column with greater efficiency. These are concepts you're going to find echoed by just about every major figure in the hobby today.

I really want to know where all these "excess column nutrients = algae" ideas are coming from. Everyone espousing it seems to credit Diana, but this clearly isn't what I've seen advocated by her or any other major figure in the hobby. The only exception would be the ADA line of products, and I watch algae happen in ADA spec tanks exactly as I'd expect for a nutrient limited column with high sediment under high light.

-Philosophos

aquatic_clay

In my aquariums the only time I've ever had algae problems is when I haven't dosed enough nutrients. When I start dosing more the algae will go away since the plants start to out compete the algae.

Clay

snail_chen

definitely not light on for 24 hrs! Plants need rests but algae don't!