NO3, test kits...and GDA and BGA

[cheeboonyong]

Sorry for the lengthy post

I've been getting hit by GDA (Green Dust Algae) consistently. All my plants have been growing well except for the slow growing ones like Anubias and Java Ferns which seem to be easily overwhelmed by the GDA.

I have been using the EI method all along. As I did more reading online, I think my problem has been that my NO3 is too hard and my plant mass isn't enough. I've since added more plant mass but it's still more towards the ADA Zen look instead of the heavy plant mass Dutch look.

So, I've decided to move towards the ADA method, where they try to control the NO3 down to almost 0 ppm.

As a preface, my CO2 ppm is very high. Definitely not an issue. Plants are pearling like crazy and CO2 test kit is showing almost green/yellow.

I've stopped dosing my Lushgro Aqua (it has N in it) and Calcium Nitrate. Now only dosing Micros, Potassium Sulphate (for K), Potassium Phosphate (for P), Magnesium Sulphate (probably unnecessary but I did anyway). I have Corals chips in the filter for Calcium.

After about 3-4 weeks, I noticed that my NO3 has dropped from >25ppm down to between 10-25ppm per the test kit. Not down to 0 ppm.

So I believe the NO3 is still not 0 ppm probably due to the fish food that I'm feeding. That's alright in my opinion and unavoidable. Also, my plants are still growing but definitely slowing down, which is what I expected. Also, my GDA has reduced significantly. Not completely gone but very little to the point where I only need to wipe my glass once a week, instead of having to wipe 2-3 times/week.

Here's the strange thing. NO3 is still not 0 ppm but I have now been hit by BGA (Blue-Green Algae or Cynobacteria). Here's the part that I am confused. I thought BGA is usually a sign of zero nitrates. My test kit is still showing 10-25ppm but I have BGA now.

I know my test kit is still valid (expire 2023) and I've tested our tap water twice where it's really 0 ppm, so I'm not doubting the test kit results.

So, question is, can BGA appear with >0 ppm NO3?

I'm wondering whether I should start dosing NO3 again.

Anyone else has similar experience?

[gimhchng]

This is an interesting post, i would like to know more about this topic too. I don't have test kit but facing similar issue, but i got it the other way round. I was facing BGA issue, and starts to increase my fert to a point that BGA under control, but GDA appears on my tank wall (still better problem than BGA to me). Only my slow growing plants like AR mini suffer quite a bit now, hope to balance it better. Recently routed my CO2 inline atomizer to after prefilter-before canister filter, with the hope to improve CO2 saturation....

[Aquariuss]

I think BGA can hit areas where there is poor circulation or when PO4 is zero. why would u want to go for zero N? Isn’t that a macro nutrient.?

[greenie]

One factor in this fight against algae that most seems unable to control is the light intensity.

Some can "mitigate" too much light by increasing distance or reducing amount of time.
Most will control concentration of macro and micro nutrient while providing unlimited CO2 by doing regular water changes to control algae outbreak.

Only those that own dimmable light fixtures and par meters can really control intensity of light in umols, is able to control algae outbreak.

Knowing how much light my plants get really helped me to control algae outbreak like GDA or GSA. I have tried controlling nutrient fertilization using auto dosing controllers and yet suffers from GDA or GSA. I have good water circulation yet still have these algae outbreaks.

Only after using PAR readings from my Seneye reef and setting down my diy LED lights to not more than 50umols did the outbreak stop. I even remove all the powerheads I used for " better circulation" and GDA or GSA outbreak disappear.

Now I simply monitor nitrate weekly because I'm keeping CRS in a "High Light" planted tank. Both my Rotala "Ramsodir" (high light) and many Bucephalandra ( Low light) seems to respond better to this light intensity.

I previously was blasting way to high on the intensity in the region on 250 - 300umols even though my diy LED was custom with various led colour spectrums similar to ADA LED fixtures.

Maybe when it comes to algae outbreaks, we need to revisit light intensity as a possible cause if everything else is already managed.

[cheeboonyong]

I think BGA can hit areas where there is poor circulation or when PO4 is zero. why would u want to go for zero N? Isn’t that a macro nutrient.?

Not really going for Zero N. My bad, wasn't clear.

Going for 0-10ppm N in the water column would be more accurate. Supplement with substrate fertilizers so that it doesn't get into the water column

Idea being that it would deny algae N in the water column

[cheeboonyong]

One factor in this fight against algae that most seems unable to control is the light intensity.

Some can "mitigate" too much light by increasing distance or reducing amount of time.
Most will control concentration of macro and micro nutrient while providing unlimited CO2 by doing regular water changes to control algae outbreak.

Only those that own dimmable light fixtures and par meters can really control intensity of light in umols, is able to control algae outbreak.

Knowing how much light my plants get really helped me to control algae outbreak like GDA or GSA. I have tried controlling nutrient fertilization using auto dosing controllers and yet suffers from GDA or GSA. I have good water circulation yet still have these algae outbreaks.

Only after using PAR readings from my Seneye reef and setting down my diy LED lights to not more than 50umols did the outbreak stop. I even remove all the powerheads I used for " better circulation" and GDA or GSA outbreak disappear.

Now I simply monitor nitrate weekly because I'm keeping CRS in a "High Light" planted tank. Both my Rotala "Ramsodir" (high light) and many Bucephalandra ( Low light) seems to respond better to this light intensity.

I previously was blasting way to high on the intensity in the region on 250 - 300umols even though my diy LED was custom with various led colour spectrums similar to ADA LED fixtures.

Maybe when it comes to algae outbreaks, we need to revisit light intensity as a possible cause if everything else is already managed.

I'm not familiar with what the term GSA is. Green Slime Algae? Another term for Blue-Green Algae/Cynobacteria?

Thanks for the insight on lighting.

I don't have nor plan to buy any Par meters. Seems like they're pretty expensive so not necessarily affordable to everyone. Guess next best thing is to play around with the lights and observe the outcome over time.

I do agree that strong lighting usually makes an existing algae problem worse, at least that's what I personally experienced. Not knowledgeable enough to comment whether that lighting (strong/excess) is the root cause though.

[Viper.sg]

For my experience, I have nitrate at 2.5ppm to 5ppm, and was hit by GDA. I decreased light interval by 1 hr and started dosing Phosphorus daily to target Phosphate at 0.5ppm so that my nitrate to phosphate ratio is roughly 10:1. GDA cleaned up nicely.

[greenie]

GDA is Green Dust Algae. GSA is Green Spot Algae.