Cause of BGA

[zenkatydid]

After being a member of this forum for some time, I am pretty convinced that BGA is caused by low nitrates. However, try and explain this to anyone else, and they laugh at you and call you evil for even suggesting such a thing. Everyone else seems to think that BGA is caused by high phosphates. What is right? I know that Tom Barr has done studies on this sort of thing, but is there any papers or official studies that I can point people to as proof? What can I use as an argument when confronted with this? And also, does the low nitrates thing only apply to planted tanks? What is the case with non-planted tanks?

Thanks for your help

[Purrbox]

Not exactly studies or white pages, but they are published articles by aquarists that I respect.

Steve Hampton on Algae including BGA
Chuck Gadd on Algae including BGA
Rex Griggs on Algae including BGA

[Plantbrain]

Originally Posted by zenkatydid

After being a member of this forum for some time, I am pretty convinced that BGA is caused by low nitrates. However, try and explain this to anyone else, and they laugh at you and call you evil for even suggesting such a thing. Everyone else seems to think that BGA is caused by high phosphates. What is right? I know that Tom Barr has done studies on this sort of thing, but is there any papers or official studies that I can point people to as proof? What can I use as an argument when confronted with this? And also, does the low nitrates thing only apply to planted tanks? What is the case with non-planted tanks?

Thanks for your help

Tell you what, ask them to show that it's caused by high PO4, any algae for that matter.

1.
For cause to be shown, you must maintain non limiting parameters of the individual nutrient in question.
2.
You must have enough control to have an algae free tank to start off with.
3. If high PO4 = algae causation, then why don't thousands of folks who do add high levels of KH2PO4 have algae?

No#3 cannot possibly be a cause regardless of other parameters, test kits/method etc. For that to be true, we must have all observed cases have BGA, this is far from true.

I've set up hundreds of tanks over the years and never had it until we started lowering NO3 specifically.

My PO4 levels have never been below 1ppm and typically are 1-3ppm range and have been for the last 15 years.

If high PO4 causes algae, where is my algae?
I suggest that anyone interested try this, lower just NO3 and have everything else higher and see for yourself.

Then you'll know.
It takes awhile, maybe a week, few days, sometimes longer.

But it does appear consistently if you inoculate the BGA.
Raising the NO3 back up prevents reocurrance even if inoculated.

Those are the observations........you can conclude what you wish.

Regards,
Tom Barr

[Plantbrain]

BTW, there are no published papers on this subject, not much grant money for aquariums and I do not have the time to write 100 papers on various topics for peer review and who would I send them too?

Who does aquarium planted specific peer review articles?
They generally are molecular, taxonomy, or ecology in natural regions.

Not our tanks.............

So test and use good methods and you can figure it out. Poor testing, even worse assumptions based on non specific cases, dogma etc, that is hardly "proof".

A fair argument wins if you do a good reasonable assessment and others try and follow the methods and note similar observations with many repeated trials.

You have to induce algae on purpose also, not merely measure things a week later after a full blown bloom occurs and you are scrambling to figure out what happened.

Mere correlation does not imply any cause.

My high PO4 might be due to poor CO2, or no NO3, which if either are low.......can downregulate PO4 uptake.

Why would a plant need PO4 if it's limited from no N?

It does not.

So the PO4 builds up.
Marine refugiums run much better for PO4 export if you add a little KNO3 to keep the macro algae removing PO4 rather than trying to drive both PO4 and NO3 down very low.

Same in a FW planted tank.

Regards,
Tom Barr

[zenkatydid]

thanks very much, that gives me a good start now i just gotta figure out how to argue successfully