cyanobacteria

[TremoloGreen]

Please help - I think we have cyanobacteria... it is a bright green film, mostly appearing on the gravel in sheets. We are changing 1/4 of the water twice a week and cleaning the gravel with a siphon pump at least one per week (worried doing it more will shock the fishies too much?). The film comes back in 2-3 days.

Is there anything else we can do to get rid of it? We changed the light so it only comes on for half the day. THe tank isn't in direct sunlight, but in a well-lit room with big windows. I only feed a pinch of flake food once a day, they eat it all in about a minute. We are in a very hard tap water area, which has been a bit of a battle with water conditions.

We have 4 rummy nose tetras and a bristle nose catfish in a 55L tank. It is medium densely planted with real plants. Before we got this problem, I was thinking of getting three platies too, but now I wonder if we have too many fish for the tank?

Many thanks, wise Fishnetters!

what style of tank?

how much filtration?

I wouldn't get any more fish, you're pretty well stocked for now.

Can you increase oxygenation? Does the filter disturb the surface of the water? If there's a venturi gizmo to add on then try using that for a bit. Also if you get a very fine syphon tube (like the sort used for air pumps) then you can get rid of a lot of the cyano that way. It doesn't remove much water because it's a fine tube, so you could do that every day.

Also some floating plants will help cut the light that reaches the bottom.

What's your phosphate like?

Hi, thanks for your replies.. The tank is a Marina 54L with an i110 Marina filter. We haven't changed the foam media sponges since we got the tank 4 months ago, but we do wash them out when we change the water. We weren't sure if it was beneficial to change them as they are full of bacteria the fish need? The filter does disturb the surface of the water.

Our sticks don't test for phosphates, just pH, nitrite, nitrate, carbonate and general hardness. I can get some that do. What should I be looking out for?

Thanks for all the other tips.

Yes, you shouldn't throw away sponge media regularly unless it is activated carbon (although carbon is unnecessary in most tanks anyway). Washing them in tank water and putting them back is the exact right thing to do.

Your local fish shop might be able to test for phosphate. If it's high then you can get phosphate removing stuff. Phosphate levels can be high in tap water in some areas and there's also phosphate in a lot of fish foods so it can get into the water that way.

Have you got any live plants in there? If not then I would turn the lights off completely for now. If so then consider adding more plants to try and starve the cyanobacteria.

You could also cut back on your feeding slightly to see if that helps.

The only effective treatments I've read about for cyanobacteria is using a complete three day blackout on the tank (no light at all, tape it up so it's pitch black) and full antibiotic use.

Be very careful with this bacteria, it can be very toxic!

Yes, I think it is especially toxic to dogs so if you have a dog then make sure he/she can't get to the water bucket or any of the equipment. Not sure how toxic exactly but best to be on the safe side.

I have managed to get rid of it from a fully planted tank without blackouts or antibiotics so it can be done- was bloody hard work though!

That's good to hear you managed to treat it EauRouge. Touch wood, I've not had it in my tank yet!

It's bloody horrible and I swear it doubles overnight. It was pre-DDs so I had plenty of time to spend doing loads of hoovering up with a tiny little airline and I stuffed as many fast-growing plants in as I could.

Hullo! Sadly, I'm back, as despite my best efforts, I could not get it all. We really thought we had nailed it at one point too

So, I've ordered some of the hard stuff online (erythromycin). Just wondered, obviously I will scrub everything before I start dosing the tank but do I need to chuck anything away (plants, driftwood etc)?

Plan is to clean, scrub everything, including the gravel as best as possible and chuck out the filter sponge but keep the filter aerating. Then total blackout while I do the four doses over four days as per the packet instructions (I think there is a couple of 25% water changes before the last two). Will this be enough to get it all, or should I consider just binning all the plants and starting again?

My poor fishies, I feel like such a terrible owner