Dirty Tank? Let's Clean It Up!

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It starts out slowly.  The first day you get your fish, your tank is sparkling clean.  A few weeks later you notice the tank is looking a little cloudy.  You ignore it.  Two more weeks go by and your fish tank is starting to look like mine did.  This can be very overwhelming for a new fish owner.  Don't sweat it, I've got you covered.  Just follow this step-by-step instructable, and before your fish know what's happened they'll have a fresh, clean tank.

Step 1: Background

Before beginning the tank cleaning process it's important to note a few things first.  This instructable is designed for small to medium sized tanks (5-20 gallons). The instructable is also designed for freshwater tropical fish, meaning that the water temperature is meant to stay in the mid 70's.  The tank that I am demonstrating on is a rare case.  It is much dirtier than it should ever be.  Most cleanings should not wait until the tank is this dirty.  In fact, every other week you should plan on cleaning your tank.

Step 2: Materials

Aquarium salt.
Water conditioner.
Fish net.
Temporary fish tank.
Water siphon.
Clean container.
Large bucket for waste water.

Step 3: Unplug Electrical Devices

The first thing you will need to do is unplug all devices such as the aerator, filter, and heater.  I suggest leaving the hood lights plugged in and simply setting the hood behind the tank to help illuminate the tank.

Step 4: Remove Decor & Fish

Begin removing all decorations and electrical devices from the tank.  Be carefully not to harm the fish in doing so.  Once the decor is removed, you can next remove the fish.  Fill your temporary fish tank with some of the original fish tank water.  It is important to use the current tank water when filling the temporary tank as this will provide less environmental stress on the fish.  Gently transfer all fish from the current tank to the temporary tank using the fish net.  Be careful not to allow the fish to jump from the temporary tank.  I recommend having a lid cover the temporary tank.

Step 5: Vacuum the Gravel

Now, you can begin the actual cleaning process.  Use the water siphon to remove the dirty water and also vacuum debris from the gravel.  The easiest way to start a siphon is to fill the vacuum end with water and then move the siphon quickly up and down several times.  Make sure you have a large enough container in place to catch the water as you siphon it out.  It is important to vacuum through all the gravel with the water siphon to remove fish waste and leftover food.  You shouldn't have any problems with the water siphon vacuuming up the gravel as it will be too heavy.  Remember to remove no more than 75% of the water from the tank. This will ensure that you do not remove all the vital bacteria that your fish need to survive.  In fact, a typical clean should only require you to remove between 25% and 50% of the original water.

Step 6: Clean the Glass & Decor

Wipe down the inside of the glass using either a clean rag or paper towel.  Do not use any cleaning chemicals such as soap to help clean the glass, as this can harm your fish.  If you own a plecostomus, I suggest leaving one of the sides of the glass untouched in order to preserve some algae for the pleco to feed on.  You may also wipe down the outside of the fish tank if needed.  Be sure to rinse off any decor items as well by simply running water over them.

Step 7: Refill the Tank

You are now ready to refill the tank.  Begin by replacing all decor items including the heater and aerator.  Do not plug these items back in yet.  Grab your clean container and begin filling the tank with tap water. Try to refill the tank with water as close to the same temperature the tank initially had. You will want to fill the tank about 90% full to allow room for the aquarium salt, water conditioner, and fish. You may now plug in all electrical devices.

Step 8: Add Salt & Conditioner

Now that you have gotten all you water added and heater plugged back in, you are ready to add the aquarium salt and water conditioner.  Read the instructions carefully for both chemicals, and add the recommended amounts of each into the tank.  Allow the tank to sit for 15-20 minutes while the chemicals diffuse and the water temperature balances out.

Step 9: Return Fish and Enjoy!

You may now return your fish to their new and now clean home.   I recommend cleaning your tank every other week.  In doing so, a 25% to 50% water change should be fine.  You should also change the filter every other week.  Be sure to stagger the interval between your filter change and water change in order to preserve the helpful bacteria and to lessen the shock on your fish.

Step 10: Important Tips & Warnings

1. Make sure your new tank water is the same temperature as the water the fish are currently in. This will reduce the shock on the fish.
2. Avoid leaving your fish in the temporary tank for more than 30 minutes.  Eventually they will run out of oxygen if left for too long without an aerator.
3. Avoid frequent large water changes.  Typically you should only change between 25% and 50% of the water.
4. Never use any type of soap products to clean the tank.  Soap has harmful chemicals that may kill your fish.
5. Never try to move a full fish tank.  They are much heavier than they appear, and this will most likely end badly for you and your fish.

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    69 Discussions

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    King_Juan

    Reply 19 days ago

    A little algae is fine, some aquatic pets actually eat that stuff, but too much isn't good for your tank or pets.

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    sundragon

    26 days ago on Step 8

    Pro tips: Wipe the glass first and then clean the stuff inside... THEN siphon the water out. If you wipe the glass and clean the interior last, all the stuff you wipe off will fall into the water and make it look like the "After" picture... Algae that's floating around will become waste as it dies and decomposes. Doing the wiping first, makes sure all that free floating crap gets siphoned out.

    Second Pro tip: Don't use salt unless you are treating the water for parasites/sickness. There are a number of fish that are sensitive to salt and it will burn any living plants that cannot tolerate ANY salt in the water. I learned this first hand when I tried it in my planted tank - Better to dip the fish in a salt bath if you're trying to treat them or use it in a quarantine tank.

    Cheers!

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    TamraA

    Question 3 months ago on Step 8

    Is aquarium salt for a fresh water tank??

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    KatieB206

    Question 3 months ago

    Hi everyone - I inherited a pleco and a very dirty 20 gallon tank with a filter that is now malfunctioning - water is cloudy, pleco is noticibly acting differently (he's the only pisher left in this tank - I don't know how to clean his filter or have the means to buy s vacuum to clean all the stones and mess in this tank- but I need to save him- how do I proceed?? Do I remove pleco to his own water and a temp aquarium and then completely clean this silt infested algae eater filter, which I have no idea how to clean the filter and what to replace inside filter if anything does actually need to be replaced, or what... I'm just trying to save a fish please help!?? thanks everyone!

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    amzivait

    Question 5 months ago on Introduction

    First let me say, we are first time fish owners and bought our 9 year old son a 2 gal fish tank for his birthday this year. The first fish two goldfish we got died in two days and we think the water wasn't conditioned properly. Well that made the water cloudy. My husband decided to clean the fish tank with hand soap.Yes indeed, I had a fit. He said they rinsed it good after I told him soap would kill the fish. So anyway, we bought our son another fish since the goldfish dyed. Two days later his Betta IS NOW DEAD. How do I fix this so my poor son can have a successful first fish tank. Is there any way to remove the soap residue or do we need to trash all the stuff and start over??

    Help please!

    1 answer
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    swissimsamzivait

    Answer 5 months ago

    Hi, my suggestion would be to get a bigger tank, maybe 5 gallons, you will have more success with more water volume, but since you don't have a fish right now, id advise that you cycle the tank https://www.google.com/url?sa=t&rct=j&q=&esrc=s&so.... the residue can be removed yes, but after a tonne of rinsing and rising, and rinsing some more.xD.. i also advise you read up a bit more on fish keeping https://www.google.com/url?sa=t&rct=j&q=&esrc=s&so... However, after some thorough research and patience, you should be more than successful. To add on, please dot house goldfish in the small tank, goldfish really need 30+ gallons of water volume, they are so messy that theyre waste will quickly poison them in small tanks and they die quickly.

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    LaKeishaB

    2 years ago

    I have a 30 gal fish tank every time I clean my fish get sick don't know what I did wrong a few day later white stuff is on the fish I lost two of my three fish I am also having high ammonia problem. can any one help me

    4 replies
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    AyushM3LaKeishaB

    Reply 5 months ago

    it differs how you clean it hand how many fish do you have, what kind of filtration system are you using. I would recommend you to only change about 20% fo water at a time weekly. this wont harm your water chemistry nor your fish. and use a good filtration system in your tank. for a 30 Gallon a power filter does best. with a biological filter.

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    AyeEvanLaKeishaB

    Reply 2 years ago

    Your fick has the ick u can got to a petco to get ick medicine for ur fish

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    CouinELaKeishaB

    Reply 2 years ago

    PS. you let the tank filter and run for a while before you put the fish back in

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    CouinELaKeishaB

    Reply 2 years ago

    hey, do you give the tank any time to adjust when you add the water conditioner? Also, just get a water neutralizer and adjuster tablets for your tank. If that doesn't work, it is the temperature of the tank.

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    AyushM3

    5 months ago

    Thats a great article. i want to add something. Aquarium nitrogen cycle does plays a great role in cleaning your aquarium, making it tidy. add a good filtration system in your tank.

    Aquarium Nitrogen Cycle

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    GarrickN1

    11 months ago

    Hell yeah nitrates put that fish water in your plants.

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    GarrickN1

    Tip 11 months ago on Introduction

    Algae on the inside of the tank is actually beneficial to the fish and leaving it kind of dirty for a little bit longer can actually make the fish stronger it just in case something might poison them then they can recover faster even if the other fish around them some of the other fish around them die four mine one out of four survived a rusty blade to scrape the side of the glass inside of the glass tank tank glass. I have goldfish.

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    feeshy

    8 years ago on Introduction

    If the tank looks like that, there's definitely something wrong...

    Firstly, changing the filter media? Very bad plan. That's probably got a good deal to do with why the water is so cloudy. The filter media is what houses the bacteria required to remove the ammonia and nitrite produced, only a very tiny percentage occupy the substrate and water.

    Salt is completely unnessecary for a freshwater tank, hence the name. Fish don't gain anything from it, you're just wasting your money.

    There's no need to remove the fish; that's just going to cause stress that isn't needed. General reccomended water change regime is 25% once a week. Dechlorinate the water in the bucket before you put it back in the tank. However, if the tank is in the process of cycling with fish, then more frequently is definitely a good idea.

    2 replies
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    thebriguyfeeshy

    Reply 8 years ago on Introduction

    feeshy, I disagree with your first 2 points;

    1) 25% water change monthly - more often if you have a problem or imbalance.
    2)Salt is good - I've used it in my tanks. It color enhances the fish and is good to use if there is a proplem like ick.
    I agree with your last statement - there is no need to remove the fish. The only time I may remove one is if I move it to a hospital tank for treatment - so I don't dose the entire tank.

    I believe in keeping things as simple as possible when keeping fish. If it's too much work it is not fun, and the maintenance doesn't get done.

    In my years of fish keeping and reading about it I've noticed many styles of keeping the tanks. So, if your having success keep doing what your doing!

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    WesleyG24thebriguy

    Reply 2 years ago

    It's 7 years but there's been some changes/upgrades for the better. I completely agree with you.

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    RachelP69

    2 years ago

    Hi everyone. I've never had a fish in my life. Bought a Betta and a 5 gallon tank. Unfortunately, before I began reading instructions on water/ph etc. I cleaned out the tank AND gravel with dish soap. Now it's Meyers dish soap which you can basically eat (I'm exaggerating), but still soap nonetheless.

    Thoughts/advice?

    My little Betta is still in the little bowl from the pet store. How long can it stay in the bowl?

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    AshishT36

    2 years ago

    think its sill dirty

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    rdavis56

    4 years ago on Introduction

    I have a 55 gal fish tank! I some how killed 3 batches of fish and now I'm on my 4th I don't get it my fish tank is beautiful and spotless but my fish are still dieing. I'm changing the filters when needed I add the conditioners, I don't know what's going on or why! I have 2 plecos,did have 4 baby cat fish and 2 angel fish and 2 kissie fish now I only have 1 angel fish 0 cat fish 1 kissie fish and 2 plecos.I feed them when needed and know not to over feed them and I also got my water tested and the pet store said that the water was fine for my fish..they have some kind of white stuff on them and I don't know if it's algae or not but I was told that the tank needs some algae because I have plecos. If any body has any answers please help..it's getting very expensive to keep this tank.