Thread algae and ferts


Junior Poster
Feb 18, 2005
Tank: 65 gallons
4x30 w
NO3: 25 ppm
PO4: 5 ppm
Co2: 38 ppm
Kh: 16
pH: 7.1

I change app. 15 gallons each week.
  • Limnophila Sessiflora
  • Cryptocoryne Willisii
  • Anubias Barteri var. Angustifolia
  • Hydrocotyle Leucocephala
  • Echinodorus palaefolius var. latifolius
  • Vallisneria americana (natans)
  • Lilaeopsis Brasiliensis
  • Echinodorus Bleheri
  • Vesiculara Dubyana
  • Anubias Nana
  • Echinodorus Uruguayensis
  • Microsorium pteropus
  • Hygrophila Siamensis
I have quite a lot of thread algae and beard algae. Since I started increasing the CO2 from 10 ppm it has helped, but it needs a thorough trimming once a week.
I have even seen traces of BGA, which I find difficult to believe, given the NO3, but it's there...

Any ideas?


Prolific Poster
Feb 17, 2005
Re: Thread algae and ferts

When you find out let me know. I have the same problem, though I believe mine is Co2 related.


Re: Thread algae and ferts

i've run my co2 anywhere from 30ppm all the way up to over 100ppm and have had thread algae issues for over a year. nothing i do to change things has made a alas, i just live with it and pull as much out as i can everyday. it's not a terrible amount...just enough to p!ss me off! :mad: i wish i knew the answer. :confused:


Junior Poster
May 22, 2005
Re: Thread algae and ferts

I found an interesting thing happened last week.

I was about to set up a new tank and tear down the old one, so I stopped bothering dosing ferts for the last week or two while I was preparing the new tank etc - and the thread algae started dying back. Not completely as there were still small patches of it in my Moss and Hairgrass. But quite the opposite to the rampant growth I was experiencing with full ferts and CO2 (30+ppm).

My amateur conclusion is that there is an element in the ferts it needs to thrive. Iron? Magnesium? Boron? Something in full supply while I was dosing, but became depleted when I stopped dosing, so it couldn't be NO3 or PO4 (still coming from the fish). And neither did it have anything to do with the NO3:pO4 ratio as I had it set pretty much perfect so no other algae grew at all, yet this stuff was still growing rampant.

I was also dosing Excel daily. Are all of you using Excel, or not? If not, that discounts organic carbon as a possible cause too.