Blue green algae/cyanobacteria

wisecrackerz

I'm relatively sure this thick, dark, blue green slime growing in a flat even coat all over everything in my tank (especially leaves of plants) is cyanobacteria, also known as blue green algae.

I don't have a phosphate test, but I'm relatively sure this much of this gunk means I have a fairly serious phosphate problem (as in too much). How do I get rid of this?!

I can't add any more plants; my nitrates are next to nil as it is (dirted plant only). Whyyyyyyyyy phosphates, whyyyyyyyyy?!
 

Dom90

Maybe it's a result of over feeding or too much uneaten food?


 

LiterallyHydro

Are you able to get a phosphate test kit? They aren't very expensive and could tell you if the phosphates really are the problem here.
 

Dom90

You can get a box of Fluval Clearmax to trap phosphates if you want.
Haven't had personal experience with it yet though.

 

wisecrackerz

Solution implemented. Further ideas?

Thank you for all the great suggestions!

In this particular case, I can be 100% sure that the issue is not uneaten food. It is a plant only tank, which means there are no animals (except a few microorganisms, I'm sure), and thus, no food. But, if I ever do get cyanobacteria in a fish tank, I'll keep over feeding in mind as a possible source of extra PO4-.

Unfortunately, none of the LFSs in my area carry a PO4- test kit, but I do plan to order one, now that I know they are commercially available. To me, in a tank containing only plants, which were all hydrogel-grown, a blue green algae problem of this severity is a pretty solid indicator of a high [PO4-], but if it's coming from my tap water, I need to know!

The links were especially helpful, thank you, Ken. So far, I have done the following; let me know if you think of anything else I should do.

  • Thoroughly cleaned slime off plants, drift wood, rocks, and glass. Removed as much as possible from dirt substrate, but still more left than I'd like, tbh.
  • Found and removed all parts (roots included) of some rotting plants (semi-aquatics)
  • Did 75% water change.
  • Removed extremely old activated carbon from filter (d'oh! SOOOO embarrassed that I didn't do thorough filter maintenance when I started this tank up again a couple months ago.)
  • Saved out my BB medium in a plastic baggy with some aquarium water in the fridge.
  • Added a fake moss ball (temporary) which supposedly has some kind of resin in it which absorbs PO4-, NO2, and NO3, for while my plants are less active during black out.
  • Dosed with tetracycline (a challenge for a 5G tank with the locally available powder packets).
  • Turned off tank lights, and draped with a towel for complete blackout.
  • I plan to complete the course of tetracycline (includes another large water change 2 days in), maintain blackout for 3 days, and remove any more algae and plant bits I can get out of the tank.

Am I missing anything?
 

LiterallyHydro

Looks good to me. Have you looked into a product such as I've used it in the past in a reef tank to good success. I imagine it would work for you as well unless it's the tap water that's raising your phosphates.
 

lookimawave

Has anyone tried Easy Life Excital?
Or Ultralife Slime Remover?
 

AlyeskaGirl

The cause of Cyano is most often very low nitrates. Dirty substrate or filter can also bring it on.

I had it growing down in the substrate against the glass. I suspected due to a dirty substrate but I also had low nitrates. Phosphates in my high tech tank is around 2-3ppm as I dose KH2PO4.
 

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