Need advice on Cyanobacteria

[Matt Warner]

Hi everybody. I have just returned from a 4 day break to find yet another cyano outbreak in my tank. A few weeks back I did a blackout and upped the amount of nitrate I was adding. I also improved flow in the tank and when the blackout was done, all was well and it had gone completely. I dropped the lighting period from 10 hours to 8 hours too. All was going well for a week or so after the blackout and then I go away for 4 days and the algae has returned.
My mum added my EI liquids whilst I was away and adding easycarbo too along with the co2 which is running. I really am at my wits end now as I don't know what else I can try.
Any help would be appreciated!
Thanks

 

[clonitza]

Please try and add a full tank photo.

Mike

 

[Matt Warner]

When I got back from my 4 day break, a lot of the plants were very overgrown. I was thinking that this could well of been the cause, as they were slowing down a lot of the flow in the tank, creating dead spots. Does this sound feasable?

 

[CeeJay]

Hi Matty

A few weeks back I did a blackout and upped the amount of nitrate I was adding.

Add some more

I had this when setting up a low tech a couple of years ago.
I took drastic measures having learnt that excess ferts do not harm the fish . I chucked in 2 teaspoons of KNO3 in 100l tank. It was gone in 4 days .
I have since upped my dosing and it hasn't come back.

 

[Matt Warner]

Thanks very much Ceejay! I wil try adding more nitrate then. I did do this before and one of my Amano shrimp died so I leaned off the nitrate a bit. It could well of been a coincidence though as all other inhabitants are fine. The one that died was over a year old anyway and it was quite large when I bought it, so I don't think it did too bad.

 

[dw1305]

Hi all,

I took drastic measures having learnt that excess ferts do not harm the fish

I don't agree with that, it depends upon the fish. If you keep sensitive soft water fish, water with a high conductivity is definitely damaging to them.

When I got back from my 4 day break, a lot of the plants were very overgrown. I was thinking that this could well of been the cause, as they were slowing down a lot of the flow in the tank, creating dead spots.

This is the "problem", your problem is the excessive plant growth. Systems with high levels of macro-nutrients in them have the potential for rapid plant growth, and I use plant is the loosest possible terms to include all photosynthetic organisms.

The 10X rule, positioning of powerheads to give uniform distribution of added CO2, large water change and extreme cleaniless are required in high tech systems because of this potential. The black-out, or anti-biotics, isn't removing any of that potential, it is just killing of the visible manifestation of it.

My suggestion is that you need is some stability, which will mean that changes occur more slowly. You can look at BigTom's "Bucket of mud", where he has designed a system which he can leave for weeks at a time.

Personally I would review what is really important for you in your tank. If you want a HC carpet etc you need to be high tech., if you don't then I would reduce light, CO2 and fertilisers amounts, this will lower that potential for plant growth.

I've never experienced an "outbreak" of Cyanobacteria in an established low tech tank, although BGA will be present on the under-side of the leaf rosettes of Pistia etc. I would very much associate it with the establishment phase of the tank, and I'm not convinced that out-breaks are solely triggered by low NO3 levels or dirty filters.

cheers Darrel

 

[Mark Evans]

It can also be introduced via the plant pots we receive from lfs's

On many an occasion, I've received potted plants with slight bga on them, if not cleaned priorly, it can manifest itself within the system.

 

[CeeJay]

Hi all

I don't agree with that, it depends upon the fish.

Perhaps I shouldn't have made such a blanket statement , and sensitive species will not fare well with this approach.
I only keep 'off the shelf' fish like harlequins, danios, guppies, neons, rummynose and cherry shrimp and none of these showed any adverse effects.