battling cyano (I think)

nick9one1 · Jun 3, 2019

I have a 6 month old 200 litre tank, radion gen4 lighting, sump, cheato, skimmer, doser, 8 fish, inverts etc. - A pretty standard setup.

For a number of months I thought I had diatoms - A thin brown coating to the sand and glass. It dispersed easily when mixed and came back over a few hours. I wasn't really doing anything to combat it, just waiting it out.

Recently I noticed whitespot on my blenny. So I pulled out all the fish and have them in a hospital tank with Chloroquine.

Since they have been removed, the "diatoms" got much worse. Thicker and then a few bubbles.
To begin with a thought the worst and suspected Dinos. but the cuc were happily eating it and there didn't seem to be any other effect on the tank.
After a little more reading I discovered cyano can also be brown and bubbles aren't uncommon.

I treated with chemiclean and within 24 hours the brown mat had all but disappeared. I left it in for 3 days, then 25% WC, UV on, skimmer on.

Its a week later and it seems to be coming back.

Is this definitely cyano, or some other bacteria that the chemiclean mostly kills off?

Any suggestions on curing it? I thought about chemiclean again, followed by a 3% peroxide dose twice a day?

Coralreefer1 · Jun 3, 2019

Cyanobacteria is actually brown in saltwater aquariums, whereas in freshwater, it is a greenish color. I believe that diatoms are a single called algae with a cell wall made of silica. Thus it is harder to scrape off, similar to coralline algae.
I don’t like treating my reef tanks with any chemicals. Because of this, I perform one to two water changes a week, reduce feeding, increase water flow and remove as much of the Cyanobacteria with a turkey baster as I can. These steps will help you to remove it in due time without using chemicals that can pose other negative issues.

nick9one1 · Jun 3, 2019

Thanks.
That's pretty much what I had been doing when I thought it was diatoms. 25% WC once per week sucking up as much as possible, then using the turkey baster to remove any that appeared between WC.
This kept it under control, but it was a never ending battle.

Chemiclean is ethromyacin (I think), and wouldn't make any difference to diatoms or Dino's. So pretty certain it's cyano (or something else an antibiotic would kill).

DeepBlueSeaV1 · Jun 27, 2019

How is this progressing at this point? I've similar looking on my 'year' old system. I think it's just part of the uglies and letting it ride out... seems like every month it's getting less and less. I've started truly 'mixing' vacuuming my CaribSea Fiji pink substrate on bi-weekly water changes. Not sure if it's that or just time cleaning things up.

I will also note... on new dry rock that I've placed in the system, those rocks get the same film and takes about 6 months for a good coating of bacteria on the surface of those rocks for it to burn off.

What substrate and rocks did you use?