Deep Cleaning a Fish Tank in 4 Easy Steps

Cleaning your fish tank probably won’t ever top your list of the most fun things to do.  However, it really doesn’t have to be too much of a chore if you keep your cleaning to some simple steps.  If you keep up with your regular, partial water changes this once a month deep cleaning shouldn’t be an all day project.  Here you’ll find how to clean a fish tank in just 4 easy steps that make even this deep cleaning seem like a breeze.

Scrape or Scrub Those Fish Tank Walls

The first step to cleaning your aquarium is to scrape or scrub all of that built up algae on your aquarium walls.  You know the slime I’m talking about.  It is probably the reason you are finally breaking down and cleaning your fish tank.  The easiest way to get rid of it is with a CLEANER FREE scrub pad.  Plain old razor blades work very well for glass fish tanks as well.  Usually scrubbing with the pad is easiest.  The razor blade will come in handy for that tough grime.  If your tank is acrylic you’ll need to us a plastic scraper to keep from scratching your aquarium surface.

Scrub Those Decorations

Your rocks, wood, castles, and plastic plants will need a scrubbing as well.  Even if the algae is not too noticeable on these decorations it’s a good idea to give them a once over.  This just keeps it from getting too built up.  Once this happens you’ll regret not keeping up on it.  The work will quickly multiply as algae builds.  This is an important step to regularly cleaning your fish tank.

Cleaning Your Fish Tank Filter

You should clean or rinse you filter media right in your tank water.  This keeps the good bacteria in your tank while cleaning out the filter dirt.  Only replace media if it seems clogged or like it is deteriorating.  Again it’s about keeping good bacteria.  Use a small brush to clean build up on mechanical parts.  Undergravel filters should be left in place.  The siphoning that you do next will free an undergravel filter of most debris.

Siphon That Gravel

You’ll want siphon your gravel at every regular water change and deep cleaning, to keep things from building up.  Also, cleaning the other parts of your tank will usually leave dirt behind.  Siphoning the gravel keeps the good bacteria in place while removing debris.  All you’ll need is an aquarium siphon and bucket to catch the waste water and debris.  Make sure you do not change more than 25% of your tanks water during any one session.  Fill your tank back up with similar temperature water with water.  Make sure to add water conditioner to the replacement water.

How do you deep clean your tank?

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14 Responses to Deep Cleaning a Fish Tank in 4 Easy Steps

  1. vanessa September 20, 2007 at 12:24 pm #

    I have cleaned out my fish tank and moved my fish into another tank. I had just realized that one of my guppy fishes had babies.
    I had separated the fry fishes from the parents. Is that a good idea? Or should I leave them with the rest of the bigger fish?

  2. Eric September 21, 2007 at 2:13 pm #

    Hi Vanessa,

    You got it right. It is a good idea to separate guppy fry from all other fish, including their parents. Guppy parents and many other predatory fish may eat them.

  3. lisa October 2, 2007 at 3:55 pm #

    I have an Oscar fish which is about 3-4inchs long; I recently noticed it looked like its intestines were hanging out of its body. Although, one of my other fishes has bitten it off.
    I have put methylene blue in the tank. Do you have any suggestions of what I can do? Also could you please tell me what it is?

    Thank you


  4. Eric October 3, 2007 at 10:09 pm #

    Hello Lisa,

    Sorry, but I don’t know what that intestine looking thing could be. If you’re worried about it, you could try bagging it up and taking it to a reputable local aquarium shop for some input. After actually seeing the problem might, they might be able to offer some more advice.

  5. Shari December 28, 2007 at 12:25 am #

    All of my decorations and live plants have these small “bushes” growing from every part of them. I don’t know if this is because I keep the light on a lot (my apartment is very dark; and the tank rarely gets any natural light). Should I throw away all of my decorations and plants. This doesn’t look very sightly. One of my fish died from “ick” and another has it now. I am cleaning my tank walls weekly (algae grows madly in there) and doing 20-25% water changes twice a month. What am I doing wrong? I feel like I should start from scratch again with the fish I have left … help … (Also I read that the ick treatments should not be used in tank with live plants? why???)

  6. Eric December 31, 2007 at 3:18 pm #

    Hi Shari,
    Is your tank newer? If not, have you done any serious cleaning? Sounds like your bio-filter isn’t fully established. If you are doing water changes on a regular basis, you shouldn’t have it this bad. Most of the things happening are usually caused by poor tank maintenance or a under established bio-filter. You could try adding some bacteria starter to kick your bio-filter into gear if this could be your problem. It is true that some Ich treatments can be hard on sensitive plants. Before you buy, you’ll want to read the warnings. Some natural remedies like Melafix don’t have these side effects. They also, usually aren’t as potent.

  7. Barbara March 19, 2008 at 4:06 pm #

    I have a fish tank that has been in storage for about 1 year, how can I clean it.

  8. Eric March 20, 2008 at 8:33 pm #

    Nothing fancy. Just water and some elbow grease. You’ll want to stear clear of bleach or soap.

  9. Leslie June 18, 2008 at 2:45 pm #

    Hey, I’ve had this fake plant made out of fabric in my tank for a very very long time. It has really old algae that has now turned blackish green and is stuck inside the fabric and is unable to be removed. I was wondering if the plant is ok to stay in the tank or if it will be unsafe to keep in.

  10. Eric June 23, 2008 at 6:20 am #

    I would pitch the plant. That stuff can spread and most fish won’t eat it so it won’t be going away anytime soon. It probably doesn’t look to great either. I don’t know if you have any real plants, but you might try some. Real plants are fun to keep and make a great natural background.

  11. missy June 23, 2008 at 10:24 pm #

    I have an acrylic tank approx 55gallons, with 4 turtles in it, i have a penguin 330 bio-wheel power filter, the water is very green and murky, how do i fix this?? fresh water was put in less than two weeks ago….please help

  12. Eric June 25, 2008 at 8:53 pm #

    Hi Missy,
    Take look at this post and the comments.
    There are a ton of stories with suggestions. I would look for the root of the problem. Overfeeding? Faulty heater, water too warm? Direct sunlight?

  13. Emma August 5, 2008 at 7:17 pm #

    Hi Eric. I’m a newbie aquarist with a 20 gallon tank. I’ve never done a deep cleaning for my fish tank before. Please excuse any silly questions for which the answer might seem really obvious.

    While doing the deep cleaning, should I move the fish to a different tank? Or do I let them hang about? All that scrubbing and messing around in the water would probably stress them out, right?

    I don’t get the part about rinsing the filter in the tank water. I know that we need to keep the good bacteria. But wouldn’t rinsing it in the tank just put put all the waste and junk I wanna get rid of back into the water?

    And just to clarify, during this deep cleaning I should only remove about 25% of the water right? Or is that number just for siphoning the gravel? How much water should I change during this deep cleaning?

    Lastly, I’m thinking of buying a 75 gallon tank for my growing red devil cichlid. Will I need to do this deep cleaning with the larger tank as well? I don’t know if I could reach that far into the tank to scrub the walls and siphon the gravel. I’ve very tiny arms. >_< What can I do? Some of my friends have 150+ gallon tanks. Wonder how they clean those big boys.

  14. Eric August 12, 2008 at 6:22 am #

    Hello Emma,
    You can leave your fish right in place while cleaning. If you clean your filter in your water, the debris will fall to bottom to be siphoned up. If your tank’s bacteria is well established, you can just rinse out separately. You just don’t want to disrupt too much at once. Generally, it’s a good idea to change no more than 25% unless you have a problem you are dealing with. The 25% is referring to the siphoned out water while cleaning the gravel. If you do buy a bigger tank, it will require the same regular cleaning. You really just have to find something to stand on to get up over top of the tank.