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How many hours should a tank light be on? I just got a timer and wanted to set it, because I was getting brown ich on the glass

It depends on whether you have plants or not, and how much wattage you've got over how much water. 10-12 hours is plenty, and the longest I's leave my lights on is about 14 hours. Usually if you're getting brown algae (diatoms) your wattage is fairly low, and I don't think that keeping the light on longer or shorter will help. I could very well be wrong, though, as I'm not 100% sure that that's how it goes.


Hoping that there must be a word for everything I mean...

What kind of light is it and are there plants?

Chris

non plant

I am getting some brown blah on the glass in one of my tanks. Although this is becauswe I have had the fluoro tube for a year and now it needs changing. This brown stuff comes when the tube is too old. Apparently the light quality changes when the tube is over a year old. I did an experiment and it is true.

I used to keep the tube until it went bung but then someone on this site mentioned the 1 year thing. So I thougtht I would put it out there in this thread. If not relevant to you then someone else may benefit.

Good luck with banishing the erks.


(btw I have an African Cichlid tank at home. No plants. I have the light on from 6.30 until 9.30pm only. No point having it on when I am not at home to enjoy the fish. Esp since the tank is not planted (mbunas like rocks instead) the light isn't needed for plant growth. Fish get enough ambient light throughout the day. This is another way to control algae.)

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~~~ My fish blow kisses at me all day long ~~~

If you have no plants then you can just turn the light on when your home. It's also best to limit the light on period to less than 8hours to help avoid algae growth. If this tank is fairly new then the brown algea is just a part of cycling and usually goes away a few months after the tank is completely cycled. Sometimes depending on water conditions it can continue to thrive especially in low light and you may have to look into stricter nutrient control such as phosphate or silicate removers and keeping nitrates very low. But even in my high phosphate, high silicate well water it was nearly gone within 6months of setting up my tank.