Excess PO4 and NO3 are blamed for algal outbreaks, I have shown that this is NOT true in a well planted tank with good CO2, light, traces, GH, K etc.
For this tio be true, I should be able to add these and illicit a response, but I have done this for many years and still have yet to see one. Some one will always say "but in my tank........" and then we find later that they don't test for NO3, CO2 or have some kit that reads 40ppm when it's really 2 ppm.
Generally it revolves around them having issues even keeping their tank's parameters remotely close while varying the dependent variable(NO3/PO4/Fe etc), so they have two or more issues influencing the NO3/PO4/Fe etc such as low CO2 (generally the case) or something else they over looked or assumed was correct.
Most folks that can solve their parameter issues generally are not interested in seeing how far they can push things till they get algae.
I am.
I do not think ratios are that important for all the talk folks do here.
If the plant has enough for give growth rate balance, that's about all you need to fret over.
I can have a 50:1 or a 5:1 ratio and still pretty much the same darn thing.
The cause of algae is poor plant growth, when your switch your focus away from the algae and to the plant's needs, suddenly it all makes sense.
This is universal, FW, CO2, non CO2, Marine, natural ecosystems, you name it.
You are correct that there algal spores in most places.
More light means less competition for light.
Plants are better at light competition than most algae.
NH4 is a big cause of blooms. Add some to see.
Then kill the algae and start over and try it again and again.
Try less CO2 etc, repeat the same thing. I did this the hard way and it took a lot of time, but I had no choice nor anyone that made any sense about it.
Your observations are in line with many others and my own, low CO2 and no NO3, that will burn you more than anything except adding NH4.
Generally it's a lack of something, the plants are not being provided with what they need to grow well at a given light intensity.
So it comes back to growing the plants well and you will not have algae.
Generally algae are not carbon limited(they need less and can use HCO3, the KH) wereas plants become when the CO2 drops.
Most algae are misers and can live on next to nothing, plants shut down and stunt or die and become surfaces for algal growth.
Plants have a higher Carbon requirement also.
There's also 10000's of times more plant biomass than algae in most CO2 plant tanks.
Generally the main competition is for NH4 which is very tough to measure in a planted tank.
The other issues revolve around a lack of CO2, NO3 etc, which stresses plants causing them to stop taking up nutrients and deteriorating conditions, the algae seem to "know" when this occurs and CO2 variation, no NO3 etc brings out stress responses in many algae species, which they respond to by going sexual and becoming active.
Regards,
Tom Barr |