Kenapa Air Akuarium Keruh? Cloudy White & Green Aquarium Water Fixes

You did a big tukar air on Sunday, the tank looked crystal clear, and by Tuesday the water is milky again. Or maybe it has slowly turned pea-soup green. Air akuarium keruh (cloudy aquarium water) is one of the most common complaints in Malaysian fish shops, and the good news is that it almost always has a clear cause.

The trick is to identify what colour the cloudiness is, because white, green and brown water have completely different causes and fixes. Treating green water with a bacteria product, or white water with an algae remover, wastes money and can make things worse.

Quick Answer: What Colour Is Your Water?

What you see	Most likely cause	Harmful to fish?	Main fix
Milky white / grey, appears in a new tank or after a big clean	Bacterial bloom	Usually not directly, but watch oxygen	Patience, less feeding, keep filter running
Fine white or brown particles that settle when the pump stops	Substrate dust, sand or soil not rinsed	No	Mechanical filtration, filter wool
Green, "pea soup"	Free-floating algae (green water)	Not directly; oxygen can crash at night	Cut light, reduce nutrients, UV sterilizer
Yellow / tea-coloured but clear	Tannins from driftwood or daun ketapang	No, often beneficial	Activated carbon or water changes, if you want it clearer
Cloudy plus smell, dead fish or uneaten food	Decaying waste, ammonia spike	Yes	Remove waste, water change, test ammonia

Air Akuarium Keruh Putih: The White Cloud

1. Bacterial bloom (the most common cause)

Milky white water in a tank that is less than a month old is usually a bacterial bloom: billions of free-floating bacteria feeding on excess nutrients before the beneficial bacteria in your filter catch up. It also happens in established tanks after you:

• Washed the filter sponge under air paip (tap water), killing the good bacteria
• Replaced all the filter media at once
• Did a very large water change and scrubbed everything
• Added a lot of new fish in one go
• Treated with medicine that knocked back the bacterial colony

Fix:

1. Don't do daily big water changes. It feels logical, but it keeps feeding the cycle of disruption. Do a 20–25% change, then leave it.
2. Feed lightly (every second day for a week if the fish are adults), and remove uneaten food after two minutes.
3. Keep the filter running 24 hours and do not wash the sponge until the water clears.
4. Add a beneficial bacteria starter from the bacterial & parameters control range to help the filter colony establish.
5. Add an air stone. Bacteria use oxygen too, and warm Malaysian water (often 28–31°C) already holds less of it.

Most bacterial blooms clear on their own within a few days to two weeks once the tank's cycle settles.

2. Substrate dust and poor mechanical filtration

If the cloudiness appears immediately after you add sand, gravel or aquasoil, and the particles slowly settle when you switch the pump off, it's dust. Rinse new gravel and sand in a pail until the water runs clear (aquasoil should generally not be rinsed; follow the manufacturer's instructions). Add filter wool or a fine sponge to catch particles, and replace the wool once it's clogged.

Punca air akuarium cepat keruh (why it keeps coming back)

If your tank goes cloudy again a few days after every clean, the problem is usually one of these:

• Overfeeding. This is the number one cause. Feed only what your fish finish in about two minutes.
• Overstocking. Too many fish for the tank and filter. Work out your tank's real volume in litres before adding more fish.
• Filter too small for the tank. Aim for a flow of 4–6 times the tank volume per hour, and more for goldfish and other messy feeders.
• Cleaning too thoroughly. Rinse filter sponges in old tank water during a water change, never under the tap, and never replace all media at once.
• No cycling. New tanks need 2–4 weeks to build up bacteria before full stocking.
• Untreated tap water. Malaysian tap water is chlorinated, and the Ministry of Health drinking-water standard allows residual chlorine of up to 5 mg/L. Chlorine kills filter bacteria, so always dose anti klorin (water conditioner) before new water goes in. Endap air (standing water overnight) removes some chlorine but not chloramine.

Air Akuarium Hijau: Green Water

Green water is caused by microscopic free-floating algae. It's harmless in itself (some goldfish and koi keepers even like it), but it blocks your view, and at night the algae consume oxygen, which can stress fish in a warm, crowded tank.

Why it happens in Malaysia

• Direct or indirect sunlight. A tank near a window or sliding door in a bright Malaysian home gets a lot of light, and that is the fastest way to green water.
• Lights on too long. More than 8 hours a day without enough plants.
• Excess nutrients from overfeeding, rotting plants or too much fertiliser.

How to clear green water

1. Move the tank or block the sun. Nothing else works long term if sunlight hits the tank.
2. Cut the photoperiod to 6–7 hours, and use a timer.
3. Do a "blackout": cover the tank completely for 3–4 days, with an air pump running. Most green water crashes during this time. Then do a water change.
4. Add fast-growing plants to compete for nutrients (floating plants are excellent for this).
5. Install a UV sterilizer, which is the most reliable fix for ponds and big tanks.
6. Use an algae control product only as a short-term aid, following the label. Many are unsafe for shrimp and some plants. Browse the algae control & clear water category and check each listing's compatibility notes.

Green water often returns if the root cause (light and nutrients) isn't fixed, so treat the reason, not just the water.

Yellow or Brown Water: Tannins

If the water is clear but tea-coloured, that's tannins leaching from driftwood, daun ketapang (catappa leaves) or peat. It's not dirty. Many Southeast Asian fish, including bettas, rasboras and gouramis, come from naturally tea-coloured peat-swamp water. If you prefer it clearer, add activated carbon to your filter and do regular water changes, and pre-soak new wood before it goes in. Most driftwood sold in Malaysia releases tannins for the first few weeks, so ask the seller whether it has been pre-soaked.

When Cloudy Water Is an Emergency

Cloudy water plus any of these signs needs action today:

• Fish gasping at the surface or hanging near the filter outlet
• A rotten or sour smell
• A dead fish, snail or large amount of uneaten food in the tank
• Several fish showing clamped fins or red gills

What to do: remove anything dead or rotting, do a 30–50% water change with temperature-matched, dechlorinated water, increase aeration, stop feeding for 24 hours, and test ammonia and nitrite with a water test kit. If ammonia or nitrite reads above zero, keep doing smaller water changes daily until it reads zero.

Prevention Checklist

Habit	Why it helps
Feed small amounts once or twice a day	Less waste means less food for bacteria and algae
Change 20–30% water weekly	Removes nitrate and dissolved organics
Rinse sponges in old tank water only	Protects beneficial bacteria
Replace filter media in stages	Never lose the whole bacterial colony
Keep tanks out of direct sunlight	Prevents green water and overheating
Use anti klorin on every water change	Protects fish and filter bacteria
Test water monthly, and weekly for new tanks	Catches problems before the water turns

A properly sized filter does most of the work. If your tank is always cloudy despite good habits, the filter is probably too small for the tank or the fish load.

Frequently Asked Questions

Kenapa air akuarium keruh putih selepas tukar air? Biasanya ini disebabkan oleh bacterial bloom. Ia berlaku apabila bakteria baik dalam penapis terganggu, contohnya span dibasuh dengan air paip atau terlalu banyak air ditukar sekaligus. Kurangkan makanan, biarkan penapis berjalan dan jangan tukar air setiap hari. Air biasanya jernih semula dalam beberapa hari.

Apa punca air akuarium cepat keruh? Punca paling biasa ialah beri makan terlalu banyak, ikan terlalu ramai, penapis terlalu kecil atau tidak guna anti klorin. Beri makan sedikit sahaja, pastikan saiz penapis sesuai dengan tangki dan basuh span dengan air akuarium lama.

Is cloudy white water dangerous to my fish? A bacterial bloom by itself is rarely deadly, but it can lower oxygen levels in warm water. Add an air stone and watch for gasping. Cloudy water with a bad smell or dead livestock is more serious and needs an immediate water change.

Will a water clarifier fix cloudy water? A clarifier clumps fine particles so the filter can catch them, which helps with dust. It does not fix the underlying cause of a bacterial bloom or green water. Use it as a helper, not a cure.

How long does it take for cloudy water to clear? Substrate dust usually clears within a day or two with good filtration. A bacterial bloom can take from a few days to about two weeks. Green water often needs a blackout, a UV sterilizer or a change in lighting before it clears.

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