# Will algae grow under moonlight bulb?



## Weidbrewer (Feb 14, 2018)

I'm sure this is going to be a case where people tell me that i just got lucky, but it hasn't been an issue for me. My son has a tank of Glofish tetras as a nightlight, so that tank is 100% lit by blue lights with the exception of any daylight that gets in the room (his blinds are normally closed.) As such, once every other month or so, I have to clean a few spots off the glass and decorations*. Nothing much - just a quick wipe-down.


*It should be stated that this tank is NOT planted, for obvious reasons.


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## MultiTankGuy (Jan 8, 2018)

Abi...

Algae isn't really type of plant or bacteria, but works like both. It does need some type of light to grow and takes in nutrients and oxygen by filtering the tank water. It needs both light, O2 and nutrients. If you remove one of these, it doesn't grow. I control algae in my tanks by keeping the nutrients out of the water. By removing most of the tank water every week, I remove any dissolved nutrients the plants and fish don't use. Since aquatic plants are more efficient nutrient users, they'll outwork algae for the available food. Gradually reduce the amount you feed and increase the amount of water you change weekly to 50 percent or even more and you'll see a reduction in the growth of algae.

M


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## Abi (May 13, 2018)

Thank you for the info, I have also read though that it’s not good to change more than 30% a week, doesn’t nearly emptying out all the water disrupt the nitrogen cycle? My tank is 30 gallons and full of plants and fish, I don’t fancy having to do such a huge water change every week. I do a weekly 30 % water change and the water is pretty clean, plants are growing well, fish are happy. My only issue is black hairy algae on the tips of some leaves which I would like to get rid of if possible. I’ve been told to reduce photo period and fine tune my co2 injection which I’m trying to do, but o would like to see my fish in ge evening without adding to the photo period.


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## MultiTankGuy (Jan 8, 2018)

Abi...

Someone has misinformed you about water changes. A 30 percent water change leaves most of the pollutants in the water. Both fish and plants will add to that amount until the next water change. Uneaten food and fish and plant waste dissolves in the water and makes nitrogen. Nitrogen drives off oxygen, so your tank water isn't as healthy as it would be if you removed and replaced more tank water. I'm not suggesting you remove 50 percent the next time you change the water, that would create a sudden change in the water chemistry and could hurt your fish. I'm saying to gradually work up to the point you change that much or even more. I mean, you're getting out the gear to change the water anyway, right? Why not take a few more minutes to remove a little more. The nitrogen levels will drop considerably and the fish will feel better and maybe the cleaner water will discourage algae growth.

M


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## Abi (May 13, 2018)

M, thank you for taking the time to reply to my post. I can see the point you’re making, and it makes perfect sense. Shouldn’t the filter remove the fish by products from the water though? Maybe both of us need to look at better filtration? I will take your advise though and gradually up my water changes, if it makes a difference I will let you know.


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## Deanna (Feb 15, 2017)

Red algae (hair and BBA types) do very well under blue light, which is why they are often found near the bottom of our tanks (blue light penetrates water better than other wavelengths). However, most 'moonlight' settings aren't intense enough to add significantly. If you can find a PAR reading for your blue light, try to keep it under 20.

Algae issues probably occupy the most number of posts on this forum. There is a lot known about it and how to deal with it, but you will have to do research here to get a good grasp on it. Healthy plants, by far, are the best thing possible for inhibiting algae.

Yes, filters convert some of the nitrogen stream into harmless nitrate, but you will still have organics that need to be removed and water changes (I do 50% weekly and clean my filter weekly) help the most. Purigen is also an excellent product for removing some of the organics before they break down into more dangerous things. Plus, Purigen will keep your water crystal clear. It is added to your filter.


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## Schoolofdisabledguppies (Jun 9, 2018)

In my 40 gal

I have a pleco, a lone Oto cat (It's 4 schooling mates all died in the first 3 weeks), red tailed shark, and a Chinese algae eater. There was never an algae problem. Sometimes, I have little strands of some kind of stringy algae, but my hundreds of guppies chomp them up...

I think the best algae control is a lot of fish willing to eat algae.


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