Dirty Tank? Let's Clean It Up!

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.

Comments

[Michelle Uma]

My daughter cleans her tank around 5-7days once .we have 8parrot fish and one silver arowana.I noticed that she removes water till the fish have nearly no water left and struggling.Please advice us as this seems cruel and wrong to me.She says they will be fine .So far they have survived and appear well.

[Clahner]

Remember to replace 25 percent of your water every week, we learned this the hard way if you don’t for a long time and you go to clean your tank you can poison and kill your fish with the clean water.

[KatieB206]

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!

[d.r.lewis1124]

I understand your situation if you put fish in before you let the tank cycle you’re setting yourself up for disaster the old filter is great for the start of the cycling because it could have the good bacteria already in it. Think about it this way you’re in a garage and there’s no fan in there it’s stuffy and you’re miserable. Eventually you’re going to suffocate. That is what you’re doing to the fish. Not to mention your pH level is probably off also there might be an ammonia factor in there as well. What I would do is let the water get cloudy after you remove all the fish. Then replace the filter with a brand new one.Let the water cycle through it for three weeks that will give your take enough time to balance out and you’ll be able to put in live plants also some new fish I’d also recommend a very good cleaning crew. They are these fish that are called bristle nose just say the name to your local pet shop and they will be able to tell you whether they have them or not they are excellent algae cleaners and get yourself a snake python for one final water change. Then recondition the water after removing 10% of the water if the water is needed to be removed by then. If it calls for another water change. After you use your testing tool or kit in this case. You will have to remove like 50% of the water if it doesn’t clear up. After everything is said and done your tank water should be crystal clear do not scrub the glass do not scrub the decorations leave everything in there use a plate to refill your water so it doesn’t move your rocks around.The 50% water change is only in a desperate situation is extremely dramatic would not recommend it. If your filter filters everything out after a 10% water change everybody be good to go and you will have a nice fresh aquarium for your fish.

[Qu3en52]

I have change my tank water twice in 30 days one fish dead and I can’t find the fish that dead. How much salt do I add to clean water

[puggamer789]

Change it every week, not twice every 30 days, good luck

[amzivait]

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!

[puggamer789]

A two gallon is WAY to small for both 2 goldfish or a betta. Either get a 5-20 gallon or get something smaller, like a guppy or two.

[jonesyman344]

Hey there! I’m so sorry to hear about your new fish, it can be so traumatic to lose them!

My suggestion is to let your tank fully cycle to get all the good bacteria in there first things first. Secondly, the smaller the tank- the faster a catastrophe can occur. Any smaller change in their water chemistry can shock them harder than it would in a larger tank. If you were in a 10 X 10 room with too much carbon dioxide you’d feel sick faster than if you were in 1,600 square foot home and you’d be less effected in a mansion with the same quantity of C02. Fish are the same way! I also suggest doing as much research as you can about the fish you’re interested in- putting a gold fish in a 2 gallon is going to instantly be detrimental as they produce more waste than most other fish and can grow very big fast. With gold fish I would suggest a 150 gallon ❤️ All of my advice comes from years of mistakes and lessons on keeping my fish babies healthy and happy. I have a cichlid aquarium and have had some of those babies for 7+ years! Fish are a special pet and I hope you have the best of time with your new set of fish, best of luck.

[Becky_B]

I recommend throwing everything out that was in contact with soap. Btw, goldfish need at least a 20 gallon to themselves. I don’t recommend goldfish. Betta fish need at least a 5 gallon if you want them to be happy and healthy. I own lots of betta. For a “tank” that size, you should be doing three times weekly 25% water changes. Betta fish also need a heater set to 78 degrees F. Feed them twice daily about three pellets. Goldfish also produce a LOT more waste then other fish, so they would need a LOT of water changes throughout the week, even with a filter. Be sure your tank is cycled. Look up the nitrogen cycle. Without an established nitrogen cycle, your fish will die within a couple days. Hope this helped!

[swissims]

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.

[Becky_B]

First off, don’t listen to this person. You should be doing 25-50% water changes EVERY WEEK. Not every other week. And you should only be changing the filter cartridge every 4-6 weeks. I recommend doing a deep clean plus 100% water change one every three months. It’s okay to change all the water at a time so long as you don’t change the filter at this time. 95% of the beneficial bacteria is in the filter, not the water. If your fish survive without weekly water changes, I will be surprised. And do not add salt to the tank, fresh water fish are very sensitive to salt and it will harm your plants. Only use aquarium salt for quick dips and baths for sick fish, and never in the main tank. And if you have algae eaters, they shouldn’t only have to rely on the algae on the glass to sustain them. You have to feed these fish just like your other fish. If you have anything smaller then a 10g tank, I recommend doing twice weekly 25% water changes. I’ve been caring for fish for 10 years. I’m pretty sure I know better than this person.

[TamraA]

Is aquarium salt for a fresh water tank??

[lime3D]

Yes. It doesn't take much.

[reillymike107]

Which way do the filters go

[sundragon]

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!

[LaKeishaB]

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

[AyushM3]

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.

[AyeEvan]

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

[CouinE]

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