Can cyanobacteria be cured without chemicals?

[jn]

Hi all,

Have a pretty serious case of BGA in my tank. I have stripped out most of the plants and have tried to 'clean' them manually by rubbing off the slime coating to kep them alive. Half have been put back in, and some of those have needed taking out and cleaning off again. I will treat the rest with some with potassium permangenate and put them back in but only after I have the bacteria under control.

Will frequent water changes and gravel vacuuming help me get rid of this problem? Or do I need to go with chemicals?

In a bind I could house the fish in a plastic bin for a week if there was something I could treat the entire tank/substrate with.

Any advice? Is the recommended antibiotic completely effective anyway?

Thanks!

[Caryl]

The recommended antibiotic is Erythromycin and is used as a last resort. It is a prescription only medicine. It works well as long as the cause is also fixed.

Try blacking out the tank for a week. The fish won't mind but the plants won't like it as much. They will recover though. Do not feed the fish during this time either.

[jn]

Thanks Caryl.

Blacking it out shouldn't be too hard.

Is the main cause high phosphate levels? I don't have a test kit but have been doing extra gravel vacs every week which gives me about 40% water change.

You might have seen my other recent post where I have switched to Micro granules to keep 'sinkage' to a minimum to reduce any leftovers laying around. It is making it easier to give them the barest minimum. Have also reduced feeding to 3 times in 2 days rather than 4.

It seems to be slowing down a little, mainly appearing on plants/gravel and not as much on the glass as before. Scrubbed the filter unit and cleaned the pipes and impeller (not the sponge or the media of course).

My pH is a little high but we're on bore water with concrete tank storage so there isn't much I can do about it. Nitrate probably sits somewhere between 0-5 (tap water is 10 and this gets used up in the tank so would go to 0 eventually).

I have some bright green string algae too (mainly on the glass) but it seems to have appeared since the plants started struggling. I have only left a bare minimum of plants in there figuring I didn't need the plants dying in the tank making matters worse.

Would carbon or something like phos-zorb help? Is there anything else I should check?

[jim r]

I also have this problem in one of my tanks, what is the cause ?

[Warren]

It's usually high phosphate levels and either high nitrate (over 30ppm) or no nitrate. Cyno can get it's nitrogen from the dissolved N2 gas in the water or from nitrate. If phosphates are under 0.1ppm (hardly detectable on a test kit) and nitrate is 5-20ppm then Cyno has a hard time starting. Excees UV from sources like the sun or metal halide also amplify the problem. Keep direct sunlight off the tank. Cyno is very common in new tanks that have high phosphate for the gravel of other objects in the tank and no nitrate as the cycle has not even started. These are ideal conditions for Cyno start.

Find the source of the phosphate and remove it. It may be a buildup of muck in the gravel, over feeding or feeding with phosphate rich food. Check your water source for phosphate. My tap water has 5-6ppm phosphate so is useless for water changes. I have to use RO just to get rid of the phosphate...

Another method of removing Cyno is to up the light and make it and the plants grow faster. Use a gravel cleaner to suck the Cyno off everything. As long as the replacement water has no phosphate in it, the Cyno and plants will eventually burn up all the phosphate and the problem will go away by itself. It all hinges on finding the source of the phosphate and controlling it.

[Caryl]

We have high nitrates in the tap water and I don't usually have a problem with cyano, just the once when it came on infected plants.

Have a look at this. It is part of an algae article that will be in the next Aquarium World magazine...

BGA - Blue Green Algae, slime

This type of algae usually occurs from beneath the substrate, and rises up. You can visually see this happening before a breakout begins, so it always worth keeping an eye on the higher levels of the substrate.

BGA is actually not an algae but a mixture of Cyanobacteria & Algae. It grows in sheets and can have a bad smell to it.

Causes -

A) Low nitrate levels

B) Areas of poor circulation with low O2, such as the substrate

Solutions -

In my experience the best way to totally get rid of BGA is to perform a 3 day blackout on the tank. Doing this will stop the development of the algae, as no light will be entering the tank. Plants will do just fine with this, as they have a more complex system over algae that allows them to survive longer without the correct environment.

To perform a blackout it is very simple and risk free.

1) Cover the tank completely so no light gets in, i have used bin bags to cover small tanks as well as old rolls of wallpaper.. you get the idea.

2) Turn off any CO2 system that may be running.

3) Use an air pump when covered.

4) Do not feed during the 3 day blackout

5) Upon completion of the blackout, do a 20% water change. If the outbreak is really bad, it is worth checking the filter to remove any excess BGA that may be there.

In all the cases that I have done this, the algae has died totally, and the plants give a nice growth spurt when the lights and normal conditions are resumed.

[jn]

Just an update.

I didn't want to black out the tank without giving it a good clean first to make sure I reduced the chance of it coming back. (also worried about oxygen levels as masses of the stuff might have been dying away)

I stripped the tank and tossed the top layer of gravel out (worst affected). Washed/scrubbed the rest of the gravel in a bucket with a weak bleach solution (advantage of a small tank!).

The aim was to get the worst of the BGA out and to make sure phosphate was as close to nil as I could get it.

I had to air the house out to get rid of the musty smell!!

Cleaned the tank as well as I could and refilled it all. The worst of the plants got a manual clean followed by potassium permangante treatment.

The fish got stored overnight in a plastic tub with some tank water and a plant. I let the tank run overnight to 'air it' in case there was any trace of bleach left in the stones (although they got rinsed 5-6 times) since I didn't have any dechlorinator. Fish are back and are 'happy as larry'.

I'll test over the next couple of days to see if my tank is going to cycle. If it doesn't cycle I'll do the blackout and hopefully never see the horrible stuff again!!

[Discusguru]

All the trouble you went through to get rid of it and it might still come back again.

IME you most certainly get it if you're setting up a planted tank. It will go away once the tank is established and balance, and the plants are growing well.

I had it in my tank on the 4th week and treated it with era tablet once. It all dissapeared in 24 hrs and so far all is good.

ron

[jn]

Fair enough Discusguru.

I do realise that balance takes time but it had gone too far. If it does start to come back I'll get some antibiotic or something and get onto it sooner.

The tank doesn't appear to be cycling so with the plants already adjusted to my water conditions, the filter established so no ammonia/nitrite spikes hopefully I can achieve some sort of balance more quickly.

When I first set the tank up I had alot of plants but they started getting black/purple algae on them. I started dosing with flourish excel. They started to die off as did some of the algae. My tank also got to some sweltering temperatures which the coldwater plants didn't seem to appreciate too much either. I had a fish disappear in there too which I later found stuck in a crevice between the powerhead and the bottom of the filter unit from a time when the water level was slightly too high when the pump was stopped for feeding! (I'm careful about that now!)

I'm not sure if the cyanobacteria started to go crazy once I started the Excel or if it was after the fish died (the fish was mainly out of the water so didn't rot in the water but had dried up and started to go mouldy).

Being a primitive organism I can imagine it might have thrived with the extra carbon? Anybody noticed a correlation between Flourish excel and cyanobacteria

I'm hoping that with the weather cooling the whole process will get slowed down enough for me to be able to keep on top of it and that the conditions being more stable will help. :oops:

Time will tell

[Discusguru]

I don't think the florish EL is causing it cos i dose quite alot. It might have been the dying algea. More waterchange might help to rid the dying algea.

Good luck,

ron