pineapple

Why do these methods work in contravention of what seems to be found in nature?

Using simple aquarium test kits, I have measured PO4 and NO3 levels in healthy lakes which support an abundance of aquatic plant life. The PO4 and NO3 levels were too small to be measurable - nothing like as high as the levels commonly encouraged in the planted tank hobby. In these locales the lake water was very healthy, clear, not eutrophic. Algae types were neither dominant nor obvious.

While it is difficult to compare a natural environment such as a lake with an aquarium - lakes have thermal zones, areas of run-off, large dilution factors, large surface areas for gas exchange, relatively cool temperatures, and other features that aquariums do not have - the main difference I notice is that lake water is ALIVE. In aquariums, it has a tendency to become DEAD quickly, particularly as a result of chemical manipulation by the inexperienced aquarist.

IME / IMO it is all about water quality rather than nutrients - at least that is the way I tend to analyze and understand the problem or avoiding algae.

Algae prevail in DEAD water. Water changes rejuvenate the system. EI-style, which evolved in times before many people had spreadsheets etc, uses targeted dosing levels and water changes to ensure water quality is optimum. Water changes allow for unknowns to be addressed and buildups to be avoided. PPS is an analytic approach which hinges on providing enough but not too much, so as to ensure optimum water quality while having minimum water changes. When a PPS proponent fails in his/her dosing regime, they do a water change.

Nutrient dosing is just a part of the water quality story.

(Now if only that SAVE AS DRAFT button was down there I could have saved you from reading this embarrassing Plocher-like plonk).

Andrew Cribb

TWood

Yeah, but -how- does water quality affect algae? How does a water change 'rejuvenate' water in a way that's bad for algae? What is the specific mechanism? At some point, doesn't this have to come down to a molecular level where the chemistry for algae life processes don't work any more? Just spitballing...

TW

pineapple

Molecular level research is beyond the means of most hobbyists. Water is a complex media in which chemical reactions take place and solutes are transported. An aquarist has the ability to observe results of some of these changes but usually cannot understand the complex chemistry involved since the methods and tools to investigate these things are not available to him/her.

To say one compononent of healthy water is more or less responsible for the prevention of algal growth seems irrelevent. Healthy gas exchange, low particulate content etc... all contribute to healthy water. If there was one magic component (such as your suggestion of oxygen) responsible for slowing or stopping algae growing, it would have been found before now by better equipped researchers.

Andrew Cribb

TWood

I don't understand the chemical processes involved when dosing NPK, but I can dose them to the 'right' levels without any knowledge of molecular biology.

I agree that the water chemistry of an aquarium is complex, and I'm not defending my proposal at all here, it was just a thought. Art can correct me if I'm wrong, but I thought the point of this thread -was- to get to specific causes. If we're going to settle for 'rejuvenated' water then we have to open the door to Plotcher again.

TW

plantbrain

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plantbrain

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Art_Giacosa

Tom, does it then boil down to a competition between plants and algae? The reason people say you have more wiggle room with less light is that deficiencies can occur quickly when creating a high metabolic rate as is the case with higher light levels. This would imply that it's a nutrient competition thing again.

New 2 Fish

I'm curious if any of these studies, and the discussion, has taken seasonal changes into account. Is it possible that the varying day lengths,temperatures and thermoclimes, mixing,etc. may have an effect on different species of algae either inhibiting others or out competing others and then making their habitat incompatible for themselves?
Anyone have links to these studies? Would be interesting reading!

pineapple

Approaching the problem from the converse: if someone were to start a thread on "How to grow really good algae in a planted aquarium" the consensus might be better.

Andrew Cribb

TWood

Heh.

Can a post mortem be performed on algae? If a tank with algae is turned around and it all dies out, can it be put under a microscope and the cause of death determined? Might make a good TV crime show...

TW