Do-It-Yourself Tips For Freshwater Fish Aquariums

I’ve had a freshwater fish aquarium since I was probably 8 years old. Obviously, my parents helped out with that financially back then, but there was only so much they were willing to invest in it for me. I always wanted to plant my tank but I knew that opened up a whole new set of costs to maintain with lighting, minerals, fertilizers, improved biological filtration etc. I learned over time that proper care and maintenance of a planted tank using the typical Fish Store purchased tools and equipment can be a little bit more costly than it really has to be. Most recently I had a Marineland Eclipse 6 tank that required these specially designed filter cartridges that cost around $3-4 a week to replace. Most of these filter systems have custom filter media cartridges that “require” you to continuously purchase replacements. They typically use a cheap floss pad material and include activated carbon inside. You can actually achieve much better filtration at a fraction of the ongoing cost of those solutions. I thought I would collect a bunch of the tips and tricks here in this post that I’ve learned over time to save money and improve the health of your aquarium.

Lighting/Canopy

You can spend a boatload of cash on lights and hoods for an aquarium and there are dozens of options like incandescent, fluorescent, CFL, Metal Halide, LED etc. Aside from the incandescent option, most of these are very costly and the bulbs are expensive to replace. You need a hood to slow down evaporation, protect your lights from splashing, as well as prevent fish from becoming suicide jumpers. I’ve found that most of the hoods include really cheap light fixtures that also plagued with heat issues and the hoods are generally more of a pain to deal with when you need to remove them for cleaning. Anymore, the vast majority of light fixtures are LEDs because they can be fully programmable to provide the right color, spectrum, and intensity and scheduling without all of the residual heat problems but these can be a bit pricy.

A great alternative to these custom hood/light combo products is to just get a clear, hinged glass canopy/cover to fit your tank which can usually be found online for around $10. It prevents fish suicide, water splashing on your lights, and can keep the heat out from the lights.

For lighting you can use one or two or more incandescent clip-on lamps with some CFL bulbs, depending on the size of your tank. Walmart carries a decent lamp for around $14. If you are planting the tank, you want to make sure to balance the amount of light so it isn’t overkill, but still provide enough that things will grow well. You also need the right color temperature to promote photosynthesis. For typical freshwater tropical plants, you want to use bulbs rated at 6500K that are usually categorized as “Daylight” bulbs. On average, you want the equivalent of around 3-5 Watts of lighting per Gallon of tank water. With CFL bulbs they usually have an equivalent Wattage rating in terms of the amount of light they provide compared to a traditional incandescent light bulb. A 9-11 Watt CFL bulb can usually produce in the range of 30-40 Watts of equivalent light output. So, for a 10 Gallon tank you wouldn’t want more than two 5-9 Watt CFL bulbs rated at 25-30 Watts equivalent or maybe one 60 Watt equivalent. I’ve found using at least a couple lights evens out the distribution in the tank and provides a more balanced look and avoids dark spots. The wider and deeper the tank, the more lights you may want to use. Of course, the clip-on lamps are fully adjustable so you can aim them however you want into the tank to achieve the desired effect. You may want to have a little more shadow in one area so your fish aren’t always blinded by the light or for plants that prefer more subdued or indirect lighting. For a planted tank with fish, I would generally recommend giving your fish some places to hide away from the light under rocks, or wood, or decorations etc. anyway. It is good to plan these things in your head or on a rough sketch, when you are designing out how you want your tank to look. Aquariums are living art, so you should put your creative thinking cap on to plan your own unique aqua-scape to enjoy and share with others.

Filter Media

There are many different varieties of filtration options like Under Gravel, Sponge, Hang On Back (HOB), Canister, or Overflow Sump. I’m going to focus on the HOB type filters, since they tend to provide the best bang for the buck for filtration, water flow, and alternative media options for the small to mid-sized aquariums. Many aquarium kits come with an included filter or pump. Some systems have them built-in. Most of them come with some sort of filter cartridge that typically provides mechanical and chemical filtration like a floss pad and activated carbon. These cartridges are usually custom fit designs that only work in the particular brand and model of filter, since they are designed to fit into a custom slot. You are made to feel locked in to buying these filters from the manufacturer as long as you have the particular pump or system. If you are doing weekly to bi-weekly water and filter changes, as you should be doing for a healthy aquarium, the cost can add up. Typically these cartridges will start around $3 each for smaller ones. The larger the cartridge the more they will usually cost. Some filters may require 2 or more of these cartridges. Buying in bulk can help reduce the cost but, regardless, the cost can add up.

Mechanical

You don’t need to be held hostage by these custom filter cartridges from the manufacturer. Aquarium filters are nothing more than traps that usually use 3 methods of filtration: Mechanical, Biological, and Chemical filters. As long as you use material that can meet these 3 filtration needs, you can maintain a clean and balanced tank. There are much cheaper alternatives that can do a better job than what is pre-packaged for you by the manufacturers and fish stores.

Poly-fil polyester fiber

For example, you can buy Polyester Poly-fil in these huge bulk bags at Walmart for around $5-9 a pop. This is the stuff they use to fill stuffed animals, quilts, and pillows etc. This stuff is excellent as a fine mechanical filter media for a fish tank. You don’t need much of it and it can filter most of the visible stuff out of the water for you. It is synthetic polyester which is a plastic derivative. It does not leech anything into the water and is not harmful to the biology of the aquarium. Since it performs as fine mechanical filtration, it will need to be rinsed and cleaned more frequently. It doesn’t have to be replaced if it is thoroughly rinsed. But at $5 for a huge bag you are talking about a few pennies worth maybe at each change. I change mine every 2nd to 3rd cleaning and water change but just rinse it out in between. I bought a 20oz bag from Walmart. At the rate I use it, it just might last for the remainder of this tank’s useful life.

You can also buy bonded floss pads in bulk from many of the online fish retailers at fairly low cost. These pads provide a coarse filter layer followed by a finer filter layer and are usually blue on one side and white on the other. They can be cut to fit any size media tray or housing.

The challenge is figuring out how to contain the media in the filter pump. Depending on the setup, you may be able to use one of the custom manufactured cartridges as a starting point. Remove the floss and the carbon the manufacturer included and just use the plastic frame to lay your bulk floss pad or poly-fil on top of. You may also be able to put your own re-chargeable chemical media bag, like Purigen, between the floss pad or poly-fil and the plastic frame. With this kind of setup you might spend pennies per filter change instead of several dollars. I did this with the little acrylic Marineland Eclipse tank I used to have.

InTank Aquatics Media Basket

For my BioCube 14 I bought an InTank Aquatics media basket to place in my sump chamber. I am able to use a sponge, poly-fil, ceramic media, and Purigen all stacked top down. Originally I had to modify the sump opening to allow the acrylic diffuser tray to fit. I ended up recently finding a custom 3D printed diffuser tray on Etsy that works much better. If I had not previously modified the sump chamber wall for the diffuser tray from InTank, it would have fit perfectly by default with the original design. Instead, I had to get creative and silicone in place a small custom cut piece of acrylic I got at the hardware store.

Chemical

There are quite a few options when it comes to chemical filtration media. Probably the most widely accepted choice is activated carbon. Carbon is ‘arguably okay’ for a non-planted tank, but can leech out trace minerals your plants need. It also has to be regularly replaced at least every one to two weeks. If you are ever needing to treat the aquarium with medicine, you have to remove the carbon filtration to keep from removing the medicine prematurely.

Media Bags

You can get cheap media bags online or at your fish store and a bulk container of activated carbon. This would be much cheaper than buying the custom cartridges with the same stuff in it. You just need to thoroughly rinse the new carbon in the media bag before placing it in the filter. Personally, I think that continuous carbon filtration is actually less healthy for any kind of tank. I believe there are a lot of important nutrients and minerals it strips out of the water that are beneficial to both the fish and plants.

Seachem Purigen

My go to product of choice for chemical filtration is Seachem’s Purigen. I posted about this magical product here, previously. It is a very fine polymer resin consisting of very tiny micro-beads that trap much of the organic waste products that are dissolved in the water. You can buy it in bulk containers but that requires that you purchase the special media bag to hold it. The resin beads are so fine that they will fall right through a typical media bag. They sell it in 100ml pre-packaged media bags. This is perfect for tanks up to 100 Gallons. The smaller the tank and the less fish and plants, the longer the Purigen will last. A 100ml media bag will last at least 2+ months in my BioCube 14 which is about 11 Gallons, moderately planted with Java Fern, Anubias Nana, an Amazon Sword, Bucephelandra, and Java Moss as well as a moderate bio-load of about 12 fish. The great part about Purigen is that it can be taken out of the filter and recharged for multiple uses. It has to soak for a day in a bleach/water mixture to release all of the collected organic waste and then rinsed and de-chlorinated for at least another 12-24 hours before it can be reused. I’ve got 2 pouches of it so I can just simply swap it out when the old media bag needs to be recharged. Purigen can have a very long useful life. I’ve read stories of people using the same Purigen media for over 5 years. I have not found any indications of how many rinse cycles it can endure before it should be replaced. At about $8 per 100ml media bag, that is dirt cheap over that length of time. So far, I’ve been using the same Purigen bags for the past 4 years and have recharged each one 2-3 times. While this works great in a freshwater planted tank and I have had very good luck with it, I may be a bit more cautious if it was for a Reef tank and I had live corals. Of course, if you are into building coral reefs, chances are high that money is not too much of an issue as buying new Purigen would be a relatively insignificant expense compared to the typical expenses involved with maintaining a thriving coral reef system.

Biological

There are a lot of different thoughts and viewpoints on this topic with respect to the best or most appropriate options. You definitely need some form of it to help maintain balance in the nitrogen cycle. Biological filtration provides a place for the beneficial nitrifying bacteria to collect and hangout to do their job of converting toxic Ammonia into less toxic Nitrites, and Nitrites into even less harmful Nitrates. This can be a sponge, ceramic media, a bio-wheel, or bio-balls. The debate is over using anaerobic only bacteria (underwater biological media) versus a wet/dry setup like a bio-wheel or bio-balls which benefits from both aerobic and anaerobic bacteria as it is repeatedly exposed to air and then splashed with water. This can let you colonize both nitrifying and de-nitrifying bacteria providing even more beneficial biological filtration. The exposure to the air allows de-nitrifying bacteria to colonize and potentially convert some of the Nitrates and off-gas it as N2. Many of the HOB filters do not have a wet/dry option. They can only provide a place for submerged media like a sponge etc. The Fluval C-Series HOB filters provide a wet/dry media stage, in addition to removable housing for each of the other media stages. This is a great option if you want the wet/dry biological option and do-it-yourself filter media. The Fluval Aqua Clear filters are another good option, as they provide a media basket where you can place your own media. Their only downside is they can not support a wet/dry media option.

A sponge is an easy choice for biological filtration. They are cheap. They come in all different sizes, thicknesses, and varieties of porousness. They can be easily cut to fit any opening or enclosure. They can also be easily rinsed, squeezed, and replaced if necessary. The ceramic rings and bio-balls are a more permanent media, whereas you will want to eventually completely replace any sponges. They provide a little better surface area for bacteria to colonize. They also provide better water diffusion in a wet/dry setup. The challenge with this biological media is it does have to be cleaned from time to time to shed the dead bacteria. It is possible to throw the tank’s nitrogen cycle out of whack if you take 100% of it out and rinse it all at once. Even if you follow the recommendations to do a partial rinse, it still has an impact on the tank’s cycle and you’ll need to monitor the tank’s ammonia and nitrate levels closely for at least a few days to a week until it regains the balance. If you get a couple of media bags and split the bio-balls up into two bags, then you can just take one out and rinse it at a time.

Recently, aquarium hobbyists have more frequently been converting to using K1 Bio Media, instead of the ceramic rings or tubes or bio-balls. The benefit is that the K1 media is self-cleaning. You suspend the media in a filter chamber and run an air diffuser/bubbler underneath it to cause the media to continuously agitate and move around. This causes all of the dead bacteria to continually shed away through the natural movement and reveal new bacteria growth underneath. This has been used for years in commercial fisheries and is now gaining quite a bit of popularity among the serious hobbyists. It is a little more expensive than the bio-balls or ceramic options, requires a decent amount of filter/sump space to house the media so it can freely float around, and it requires a strong bubbler action to agitate the media, but it basically is a no maintenance option.

Custom Aquariums ceramic biomedia balls

I have recently switched from using plastic bioballs in my sump media basket to Custom Aquariums ceramic biomedia balls separated into 2 media bags. This allows me to swap half the media out to rinse and clean it every couple months or so without disturbing the other half of the media. This should help sustain a thriving nitrifying bacteria culture and prevent the media from turning into a trap for toxic organic materials.

De-Chlorination

The majority of municipal water supplies, as most freshwater hobbyists already know, contains chlorine or chloramines to kill any contaminants. This can be toxic and potentially cause your fish to die. So, when performing water changes, the new water needs to be treated with a de-chlorinator that will combine with the free chlorine in the water to make it harmless. It is best to treat and store this water in advance, if possible, so that it has a little bit of time to age. Easier said than done when you have a larger tank and need to do 20-40 Gallon water changes Most of the commercial de-chlorinator products are just a solution of water mixed with sodium thiosulfate crystals. Depending on the product, where you buy it, the quantity, and the volume of regular water changes you are performing, you can spend quite a bit on this chemical. Alternatively, if you can install a Reverse Osmosis water filtration system in your house, this can be ideal. I found my basic system at Costco for about $180. I did have to go to the hardware store for additional parts so that I could attach my drain hose to my disposal. I also added a passive pump to improve the efficiency and refill time.

Seachem Safe

Now that I’m using Purigen which requires a chlorine bath to recharge it, I will be needing a fair amount of de-chlorinator for the rinsing solution. Instead of buying the commercially mixed and diluted product, I can just buy either Seachem Safe or a half-pound or pound of sodium thiosulfate crystals and mix up my own treatment solution. This method will cost pennies on the dollar and be every bit as effective. A half pound of the crystals for a few dollars can treat around 50 to 80 times the amount of water versus the small bottle of commercial products which may be able to treat in the neighborhood of 1000-1500 gallons. For rinsing and de-chlorinating Purigen after soaking it in a bleach solution, it takes 2 Tbsp of de-chlorinator per cup of water. To submerge the Purigen you will probably need at least 2 cups of solution. That is almost 60ml of de-chlorinator which is roughly half of the typical small sized bottle or enough to treat around 600 Gallons of water. At typical retail prices that is fairly expensive.

Feeding Plants

Eco-Complete Planted Tank Substrate

If you plant your aquarium, aside from the water, it is fairly obvious that you need 2 things to help them grow, light and nutrients. I covered DIY lighting earlier. For nutrients, it is best to use a substrate like Eco-Complete or Organic dirt capped with gravel and/or sand that can feed the roots and even release nutrients into the water column. In the absence of a nutrient rich substrate, it is even more important to place fertilizers in the substrate and dose nutrients into the water. Any fish in the tank will produce ammonia which will eventually get converted by the nitrifying bacteria into Nitrates which the plants will find useful. But plants can not live (grow) on Nitrates alone. It is important to provide a source of carbon. This is typically achieved from any carbon dioxide that may be present in the water. However, CO2 won’t just magically show up dissolved in the water. So, many people who keep freshwater planted aquariums will ultimately dose CO2, using a fairly costly setup with a CO2 tank, regulator, tubing, and diffuser/bubbler. While this type of setup can produce tremendous growth with plants, it is usually expensive and can make it more complicated to keep the tank’s pH in balance.

Seachem Flourish Excel

A cheaper alternative is to get a bottle of Seachem Flourish Excel to regularly dose into the water every 2-3 days. This is essentially an organic carbon chain in a liquid fertilizer form. This is not a substitution for CO2 but a photosynthesis intermediate that helps the plants in the carbon chain building process.

Aquarium Co-op Easy Green Fertilizer

Another great option I discovered is the Easy Green fertilizer from Aquarium Co-op. The 120ml bottle is $10. You only need to add 1 pump a week per 10 gallons for a low light tank or 2 pumps per week for moderate lighting. I dose twice a week in my BioCube which is ~11 gallons and I have calibrated the PAR output of my LED lights to a moderate level set at 60% on my BlueFish controller measured using the Photone app on my iPhone. I have been using the same bottle of Easy Green for almost a year now.

Alternatively, or in addition, you may use a refugium, which is a fancy name for a holding tank/reservoir that is separate from the display aquarium but usually in line with a sump filter system and hidden underneath. A refugium is typically used to hold various plants, micro-algae, and copepods etc. that are lit up during the night time hours as a way to continue introducing oxygen into the water through photosynthesis, while all of the plants in the display aquarium are not and may potentially be absorbing some of the oxygen from the water. That nighttime oxygen absorption problem is not as significant as some may make it out to be. Plants will actually store some of the oxygen they produce for use at night.