Dirty Tank? Let's Clean It Up!





Introduction: 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.



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    61 Discussions

    Hell yeah nitrates put that fish water in your plants.

    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.

    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

    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!

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

    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

    3 replies

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

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

    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.

    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.


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

    think its sill dirty

    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.

    6 replies

    Hey bud, the white spots on your fish is more than likely ick, a very common disease fish can get. And what i would recommend is putting the remaining fish you have in a small holding tank for a few days while you clean and disinfevt the tank you currently have. A great way to clean it without chemicals is with 20 mule team borax. Its in the laundry aisle at the supermarket, and its a naturally occuring mineral (its actually a crystal that is ground up, which has amazing properties of healing, disinfecting, and cleaning. So once your tank is clean you might wanna think about replacing the sand or gravel as well but if you can't or don't want to you're gonna wanna tell your tank with distilled water. Tap water nowadays, and even purified water, and in some cases (walmart) even the distilled water has flouride in it, which is poisonus to every living organsim on earth. I'll guarantee thats what your problem is. You can make a home distiller for about 20 bucks and turn water from your hose into pure H2O! I would suggest investing in that cuz buying distilled water by the gallon can get quite expensive depending on your tank size. And just remember that outting in fresh water in a clean tank means that there will be no bacteria in the water that the fish need to servive, so ask your local pet store for a gallon or so of their tank water cuz youre you're starting up a new tank. And something i tried that worked better than anything i could have ever imagined to get rid of ick without chemicals, was just a tabelspoon of colloidal silver, a ruby that cost $2.00 from a gemstone store, and a clear quartz crystal. My Moms friend suggested it i told her she was crazy, she took offense came over to my house amd put it in herself, and within 20 minutes the ick was gone. Which up until then i couldnt get rid of it for the life of me. (Shoulder shrug) Idk how or why but it worked.

    I'm assuming that the issue was resolved by now, or you got rid of the tank... but for other readers that may be having trouble with similar issues. Please use the forums and aquarium hobbyist websites to help you determine what fish will work well together in a tank. http://www.fishprofiles.com was the one that I learned so much from when I started keeping fish in high school. 10 years later and I'm still a member helping newcomers to the hobby.

    As for the fish, they are uncompatible to live together, and if there is not enough algae in the tank for plecos, you can feed them leafy greens, zucchini, or other veggies (do your research first though) until the tank gets a little more healthy and green! There are also algae tablets that you can buy to feed them, but they are pricey!

    I work at pet smart the thing wrong is that u cant have other fish in the same tank same thing happend to me and they kill each other the catfish is a bottom feeder and wont survive im sorry

    Your fish have ick or ich it's potentially deadly but you can save them... There's lots of info online... Good luck...

    rdavis56 Sounds like you have a bad case of Ich. Most likey from your petstore. http://en.wikipedia.org/wiki/Ichthyophthirius_multifiliis


    I have a 55 gal tank and I can't figure out why I keep having my fish die on me! I started with 2 dalmation mollies, 2 red velvet wags, 2 guppies, 1 algae eater and 11 neon tetra fish... All of them are small with plenty of room. My male wag died the very next day so I went and bought another one and he died after 4 days, now I have 3 or 4 tetras that are going belly up! Checked the PH levels and they are fine, filter is working, bubble machine is on low to medium and I've got 2 live plants in the tank. I don't see anything on the fish and I take the dead ones out right away. What's going on? Any suggestions?

    1 reply

    Did you let the tank cycle properly before adding fish? Sometimes people don't realize that a fish tank is actually an ecosystem and think "add water and fish" but in reality it takes a little more time to make something that will thrive and be beautiful.

    If the tank has been set up longer, then it could be any number of other things. Without more explicit information we can't really determine what's going on in your tank.