Interrupted lighting and BGA

nid

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Sep 30, 2005
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I have a 40 gallon planted tank with DIY Co2 and about 1.5 wpg light. I have been semi successfully battling an outbreak of blue green algae in the past month.

I have introduced 2 powerheads into the tank to up the flow around the tank. At every water change I remove a lot by hand. Since starting this eradication campaign the level and speed of regrowth is considerably reduced. I am wondering if this approach will eventually lead to a total die off or if I will have BGA in this tank at a low level for ever.

I have considered the total blackout approach which I know is effective as I used it in a new tank I rather cleverly infected whilst fishless cycling. A 4 day blackout killed it all. I do not wish to use a blackout in this tank as it is stocked with Praecox rainbows, Neon tetras, Dwarf chain loach, Ottocinclus and SAE's. The chain loaches and Ottos and SAE's are constantly foraging and grazing and I think a blackout would cause them in particular to suffer.

Has anybody tried the interrupted lighting method? 5 hours on 3 hours off and 5 hours on. I have read that this can work with some types of algae, would it be an effective weapon to use against BGA? I am thinking that BGA being a cyanobacteria might mean that this method could be effective. Any replies would be appreciated.

Thanks,
 
It will not work.
Blackout works well and have no impact on any fish.

I'm not sure why people think the fish will suffer, most fish come from dim waters and are shipped in dark containers etc.

Regular KNO3 dosing will address the long term issue and prevent it from appearing.

Regards,
Tom Barr
 
Thankyou for the reply. If I decide to use total blackout could you advise me on the minimum amount of time it could be used effectively.

Could you advise me on the KN03 levels I should be aiming for to stop a reoccurence.

I am suprised that you find it difficult to understand why 'people think the fish will suffer' A four day blackout (a total absence of light) is not in any way comparable to inhabiting 'dim' (low light)waters.Remember these fish have evolved to live eat and breed in these low light conditions, not no light conditions. I accept that whilst being shipped fish will be transported in total blackness. I dont know the duration of the transportation of most fish but I suspect it is probably often less than 4 days. The mortality rate amongst shipped fish is also high.

I was concerned about the ability of 3 of my species of fish to cope with the blackout. This concern may be unfounded but is, I think understandable. I take the keeping of fish very seriously and feel that I have a moral responsibility to ensure their optimum welfare while they are in my care. It was to this end that I was posting.

As an example take two species of rodent, say a rat and a shrew. Put them both into their own cage with bedding and water but no food. Leave for twelve hours. At the end of the twelve hours you will return to find one hungry fed up rat and one dead shrew. Two seemingly similar species with very different requirements. The shrew smaller with a very high metabolic rate has to eat almost constantly to maintain a stable body temperature. If you knew that, you would not leave a shrew in a cage overnight with no food.

Thanks for the advice.
 
Well, now you changed the subject.

There are virtually no fish that cannot survive very well without food for 3-5 days. You can still feed them in ab blackout. Most fish do not require light to find food. You knbow that is true. Tropical fish are often without food for 20-30 days from wild locations. You chose to make an issue out the darkness being bad for them, then switched the question to them feeding being the issue/not being able to find food in darkness. Just come out and ask the real question you have about the fish's health.

Then I can answer the question.
A good question will yield a good answer.

3 days is the time needed for BGA blackout.
No one has ever reported any fish related issues to being in the dark.
Feeding or otherwise. Blackouts have been used for decades.


Regards,
Tom Barr
 
Thanks for the reply.

You are mistaken there is no 'hidden' question concerning the health of the fish.

The analogy I used was just that, an analogy. It was not supposed to be taken literally. I was just trying to get the point across that I had genuine concern and was worried that for whatever reason one or more of the species might be less able to cope with a total blackout than the others.

You have however reassured me on this score. I will try the blackout method in a week or so if my current methods prove unsuccessful. I have to say that increasing the current and manual removal do seem to be working remarkably well. There is still some grow back but it is very much weaker and slower.

Thanks again for the advice.
 
how would a blackout work with plants? i would think pretty bad of this with plants, but let me know if im wrong
 
It's fine. Three-four days of no light won't affect the plants much at all. Mine actually seemed to grow more, and they did -- upwards, looking for light.

I have a lot of red stems, so if plants were gonna go thfffffpt! it would have happened to me.

Roan
 
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