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Why Your Fish Tank Water is Turning Green, Yellow

Why Your Fish Tank Water is Turning Green, Yellow

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Green aquarium water is the result of a bloom of unicellular algae and is basically the result of two existing conditions. The aquarium is either receiving too much light or/and your water has a high concentration of chemicals such as phosphates. Pet Central.

Of the many water clarity issues that manifest in fish tanks, green water is a pretty common occurrence, one that many hobbyists will experience at least once in their fish keeping days.

Usually, green water in your fish tank is caused by an overgrowth of algae, aided by an imbalance of chemicals in the tank and too much light.

Green aquarium water gets its color from free-floating algae which have cells that contain chloroplast like plants and can produce energy from sunlight; Animal Mum.

As such, the most straight forward way to deal with this clarity issue is to starve the algae by cleaning your fish tank more and limiting the light duration to between 8 and 10 hours.

Algea, being a type of plant, will thrive as any other species would in your aquarium. So, please note that algae are a part of any water body, including freshwater and marine aquariums, and though unsightly, is not harmful to fish.

See more insight below.

How Do You Stop Your Fish Tank Going Green

Aquarium treatments such as green away can simply resolve green water issues in a fish tank, but they are more a short term solution. To exhaustively get rid of the green scum, you would need to do something about the underlying issues.

As I noted above, the principal cause of algae-bloom is excess lighting or too much waste in your fish tank. As such, this would be an ideal place to start.

Control these factors, and you will solve your menacing green water problem.

#1&mdashControl Your Aquarium Light

A balance aquarium lighting schedule is not only crucial at keeping your fish tank from turning green but also give your aquatic pets enough time to rest after a whole day of swimming and feeding.

In planted aquariums, adequate (but not too much) lighting is also paramount to ensure your plants grow at a reasonable rate, not too fast, and not too slow.

Generally, anywhere from 8 to 10 hours of lighting is considered adequate, though in aquariums with plants species that require high-light and consume plenty of nutrients, up to 12 hours of light is allowable.

You also don’t want to keep your fish tank too close to the window seal, with direct light exposure. This is particularly so if you have light bulbs installed in your aquarium to use while it’s dark.

A fish tank in direct sunlight all day will often develop a bloom of green water.

#2&mdashRemove Excess Fish Waste From Tank

Usually, when there is excess waste in your fish tank resulting from leftover food, fish poop, and plant debris, a chemical imbalance ensues, causing excess algae growth.

The algae growth is boosted by a surplus of nutrients such as nitrates and phosphates, which they use as food, coupled with light during the photosynthesis process.

Phosphates can come from several sources in an aquarium, but most times, it results from fish waste and leftover from commercial fish foods.

Even so, the tap water from some municipal supplies is naturally high in phosphates enough to cause spikes in your water.

That said, please note that both conditions, that is, excess light and chemical imbalance, need to be present for algae to develop, and neither alone is self-sufficient.

#3&mdashRemove Excess Fish Waste From Tank

Since sometimes it is a little challenging to keep waste from accumulating in your fish tank, a reliable cleaning schedule is recommended to ensure you remove all excess dirt that might be in your water.

Usually, most wastes sink to the bottom once they get soaked, so start by vacuuming your substrate. Gravel is pretty easy to wash, though a basic siphon vac kit will work even for sand substrates.

You will only have to deal with a little more dirt getting blown up.

Another part of your aquarium you will want to focus on cleaning is the glass. Algae seem to like clinging to tank walls and can get very unsightly, plus make your water murky.

Luckily, all you need is an algae scraper to clean acrylic or glass tank walls.

Driftwoods, rocks, and other decorations can also be harbors of algae, so clean then every once in a while.

#4&mdashAdd Algae Eating Fish

Aquarium fish have very different dietary requirements, with some showing a keen preference for all green foods, including algae.

By far, the best species to keep when you have an algae (green water) problem is Siamese (Chinese) algae eaters and common plecos. However, both of these species grow quite huge, with the latter reaching up to a foot long.

So, if you have a small fish tank, you may want to consider adding tinier plecos like the bristlenose or Otocinclus (dwarf sucker) catfish, though less efficient.

#4&mdashDiatomic Filtes and Polishing Pads

The algae that turn you aquarium water green are so small that an average filter is unable to trap them. As such, getting a more effective unit or filter media is pretty much your last resort if you try all other remedies and fail.

Diatom filters are one option you can go for. They are specially designed for fine mechanical filtration or water polishing, albeit not recommended for everyday use.

They derive their name from the diatomaceous earth powder that is used inside. The fine powder is loaded into the filter to create small pores that trap the smallest of particles.

Having said that, if trying to avoid the hassle of buying a new filter, you can do some simple modification to your unit instead.

This includes adding a polishing pad capable of filtering out even the tiniest particles from your aquarium water. All you need to do is replace the media as it traps and removes the green waste from your water.

#5&mdashUV Sterilizer Aquarium Light

An aquarium UV sterilizer light utilizes fluorescent lamps that produce light at a wavelength of about 254 nanometers to kill bacteria and algae in your water.

The light penetrates the algae causing green water in your tank, mutating their genetic material, and keep them from growing and multiplying.

Most sterilizers units come with a covered light and a powerhead, which they use to suck in aquarium water. Here is a link to the AA aquarium green killing machine, which I highly recommend.

From experience, it takes about 3 days for your tank (50 gallons) to start clearing up. By day five, you should be able to see everything inside your aquarium, with the water becoming crystal clear within a week.

Is Green Water Harmful to Tropical Fish

Green water presents little danger to tropical fish and other aquatic pets. In fact, most of them are used to similar conditions in their natural habitats (in the wild).

However, the green water can be a sign of a more serious underlying issue, most likely with your lighting or water chemistry. As such, it is recommended you take precautionary measures to keep the problem from escalating.

Besides, green-cloudy water in a fish tank is unsightly and beats the whole purpose of having the aquarium to begin with.

That all for this post, see you on the next one.

Happy 🦐🐠 keeping.

Eddie Waithaka

Resident Content Creator and Marketer at AquariaWise who talks about aquariums and fish and aquascapes a lot.

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