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/The Conscientious Aquarist

Freshwater Aquarium Maintenance


By: Sabrina Fullhart


Maintaining Your Freshwater Aquarium

As with most anything else in life, stability is often pretty nice.  So, now that you've got your tank set up and running, what are you going to do to keep it running smoothly, to keep it healthy, lively, and beautiful?  Pull out that siphon hose, right?  Well, there's much more to it than that....  

Water Changes

Out with the old and in with the new!  Aside from the fact that "dilution is the solution to pollution", you'll be replenishing your system with vital nutrients and minerals that help keep things alive and well.  A tank without a water change is like living in an enclosed room with stale air....  sure, maybe you can get by, but eventually it's going to get a bit rough and stuffy unless you open a window and change out some of your environment. <See the linked file... in blue>  

Preparing Your Water

Put down that siphon hose!  You're not ready yet.  Before you start pulling water out of your tank, let's think about what you're going to be putting back into the system.  Does your system require a special pH?  Salt or additives of any sort?  Does your tapwater have a different pH than your aquarium, or are you using purified or filtered water that will need to be replenished with minerals before using it?  If so, you might want to start thinking about preparing your new water before you take any out.

A dedicated Rubbermaid tub or trashcan or a spare aquarium can be very useful for making and storing new water for your system.  If you need to make changes to your water prior to adding it to your tank, this will give you the opportunity.  Fill up your bucket, tank, tub or trashcan with your source water (from the tap, or your tapwater filtration system) and start making whatever changes you feel are necessary.  Add your water conditioner... to remove chlorine/chloramine and more, salt, peat or bogwood, buffers, or whatever you have chosen to use in your water now.

Next, let's bring that water up to the right temperature.  Don't use hot or heated water out of the tap; the rapidly elevated temperature from your water heater can cause the water to become saturated with dissolved gasses (nitrogen, primarily) and can actually cause your fishes to contract "gas bubble disease" - sort of "the bends" for fish.  Instead, drop in an extra aquarium heater to raise the temperature of your water preparation vessel - just always remember to unplug it if ever you empty the container.

To keep this water from going stagnant it's a good idea to add some sort of circulation device.  A powerhead or an aerator with an airstone will suffice.  As long as you have water in this tub, you should have it circulating - or very, very full with little to no airspace, covered, and kept at a cool temperature if you'll be storing it for quite a while and don't want to leave a powerhead running.

Before you use your new water, be certain that it is of the right pH (and possibly hardness), has no ammonia or nitrite, and is the right temperature.  

Siphoning And Gravel Cleaning

Alright, NOW we're ready for that siphon hose.  Siphon hoses come in a neat array of sizes, lengths, and functions.  There are even some that are "powered", like the Python No Spill Clean And Fill, which hooks up to your faucet and uses the suction created by running tapwater to pull water out of your tank and down the drain.  Choose what will work best for you and your system; the idea behind all is pretty much the same: getting water out of your aquarium.

I'll take a moment here to warn you NOT to start a siphon with your mouth.  Aside from a very few bacterial complaints that can transfer from fish to humans, poopy fish water tastes horrible.  Don't do it.  Instead, put the end of your hose into your bucket and submerge the hard plastic tube completely in your aquarium, then lift up, covering the end of the tube.  As the water starts to drain down into your bucket, submerge the tube completely again to keep the water flowing.  This might take a bit of practice the first few times, but the alternative is a mouthful of dirty tank water - you'll learn quickly.

Once your siphon is running, you can start cleaning your gravel with the hard plastic tube.  Push it gently into your substrate and give it a bit of a back and forth or up and down motion to loosen detritus in the substrate and send it through the tube and into your bucket.  If you have very fine or lightweight substrate, you'll need to be very careful not to pull it through the hose as well.  Also, be thinking about the inhabitants of your tank; especially those that might live partly or primarily in the substrate, and use caution not to harm any kuhlii loaches, spiny "eels", or other substrate dwellers that might be lurking down there somewhere. 

Cleanliness is not sterility! Try never to clean "too much" of your substrate at once - remember, most of your biological filtration takes place in the substrate; cleaning this too often or too thoroughly can have devastating effects on your system by causing the tank to start again at the beginning of the nitrogen cycle, subjecting your livestock to toxic ammonia and nitrite as your nitrifying bacteria repopulate your gravel.  

In-Tank Maintenance

Once you've finished removing a portion of your system's water, you can take the opportunity to handle a little more in-tank maintenance.  Is there algae on the glass?  Decor that needs to be cleaned, moved, or removed?  Live plants that need a bit of a trim, or propagation?

If you use a scrubbing device of any sort to remove algae from the surfaces of your aquarium, keep in mind the material of which your aquarium is constructed.  If it is acrylic, be certain to always use a scrubbing pad designed for use with acrylic aquariums, and never press hard with it.  If you are cautious about it, you will likely not scratch the walls of the tank.  Glass is a lot more scratch-resistant, so you need not be quite so careful.

If you move or remove decor, remember again to be respectful of your tank's inhabitants.  Are there shrimp or loaches that may have taken up residence inside an ornament of some sort?  Will moving the ornament leave them an "escape route"?  Inspect any items with holes very thoroughly if you remove them to be certain no one is living inside them.

If you have plants to trim or propagate, now is the easiest time, while the water level is still low.  Any cuttings you remove from the system should be inspected to be sure nothing - shrimp especially - has tried to sneak out with them.  NEVER flush your plant clippings.  Instead, set them out to dry and then discard them in a sealed bag with your trash.  Flushing plants or tossing them out in the yard can be a bit of an environmental hazard, as the plants may find their way into your local waterways.

Now that you're done with your in-tank maintenance, you're ready to fill the tank again with the water you prepared earlier.

Equipment Maintenance

Periodically, you will need to inspect your equipment for wear.  A short visual inspection after your water change is a good idea.  Check to see that your water circulation devices are still functioning properly.  Keep an eye on your temperature control devices and monitor the temperature with a thermometer so you'll know right away if something is awry.  Be sure to check your filter and change, clean, or replace any media that is used up or soiled.  

Thoroughly Cleaning Your Various Equipment

Check your lighting for any mineral buildup.  Clean any algae or mineral deposits off the glass or cover of the tank (if you have one) to make sure nothing is obstructing the path of the light into your tank.  Look at the ends of the bulbs and anywhere that could possibly show you any indication of corrosion of the wiring, starter, ballast, or pins of the bulbs themselves.  Carefully clean any buildup off the light housing and tubes (you might want to unplug the lighting, just to be on the safe side).

Remove powerheads and disassemble them (refer to the instructions that came with them, or look up the manufacturer on the internet to request instructions, if you need them).  Clean off the impeller, and check for any hairs or plant material that may have gotten wound around the shaft.  Check to be certain that the impeller spins freely.  Clean out the impeller housing.  If you use a venturi device with the powerhead, make sure the hoses are free from obstruction, and if the venturi includes a small air filter, make sure this is clean.

If you use an air pump, check that your airline tubing is still flexible.  If it has gotten hard or has mineral deposits or algae inside it, replace the tubing.  If the airflow seems reduced, replace the airstone.  These do become clogged over time and can seriously decrease the output of the air pump.  A dirty airstone can also cause a lot of wear and tear on the pump from the resistance applied, so it's a good idea to replace these periodically even if you don't think it's very clogged up.

Take a look at your heater to be sure the glass tube is not cracked.  Observe your temperature to know that your heater is functioning normally.

Disassemble your filter and clean its components.  Use a clean bottlebrush to scrub out pipes and tubes.  You might even dedicate an old, clean toothbrush for helping you with this task.  Clean any gaskets or O-rings and lubricate them if necessary or recommended in the manufacturer's instructions.  Remove and clean the impeller, and clear the impeller housing of any obstruction or foreign objects before replacing the impeller.  Clean or discard/replace dirty or expired filter media.  Never completely replace all soiled media at one time if it is your primary source of biological filtration, or if you have just heavily cleaned your substrate.  Instead, replace the media but leave a portion of the old media in the filter for a while, to help "seed" the new media with nitrifying bacteria.

Maintenance Schedule

The schedule of maintenance you adopt for your aquarium is something that you'll ultimately develop on your own.  Each system is different, including the amount and frequency of maintenance its components require.  A very good practice is to make a permanent "log" for your aquarium, detailing purchases, keeping receipts handy... including a daily, weekly, monthly and more longer time frames for listing and dating when you should/have done maintenance.

Test your water frequently for ammonia, nitrite, and nitrate in the beginning to start to determine how often you'll need to do water changes for your tank.  Ammonia and nitrite should always be zero.  Nitrate should be maintained below 20ppm, and perhaps lower.  If you notice your nitrate starting to creep up a bit, use that as your cue to do a water change.

Though your system may differ, you could start off with the schedule outlined below and then tailor it to fit your system if you find that you need to do more or less maintenance of any particular part of your system.


  • Feed your fish. Some species are best fed a few times per day, others only every few days.
  • Visually inspect your fish to be certain nobody's injured and everyone's accounted for.
  • Check the temperature of the water.


  • Either this often or bi-weekly change out 20% of the water, replace with water that is stored.
  • Test your water.  If ammonia or nitrite are above zero, or nitrate is above 20ppm, it's time for a water change.
  • Check your filter media, clean or replace when necessary.
  • Clean the outside of the glass (just plain water and a clean rag, please!), and scrub algae if necessary.
  • Clean the lid/cover of your aquarium.


  • Visually inspect all of your equipment, including your lighting, powerheads, air pumps, and filters.
  • Clean any equipment that warrants it, including and especially intake tubes on your filters.
  • Trim any dying foliage from your plants and take care of propagating cuttings if you choose to do so.

....and Beyond.....

  • Change bulbs in your lighting system.
  • Replace airline tubing and airstones.


As you become more familiar with your system and its needs, you'll learn what you need to do and when.  Make a list and stick to it.  A healthy environment for your fish depends heavily upon the proper working order of the components that make up your aquarium.  Observing these components and caring for them appropriately will help to ensure the good health of your livestock, making your tank ultimately more enjoyable for your fish and for you.

Bibliography/Further Reading:

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