Many people may find it difficult to control their nitrate, as many have too many fish, overfeed, or just don't feel like doing water changes. Nitrates can also be an issue in larger tanks, as it's harder to change out such large amounts of water. This thread is the solution to nitrate - These nitrate reduction methods can reduce yearly water changes from 50+ to less than 10. The rating system for each method is from 1-5, with 5 being the best, except for cost, as 1 means lowest cost. This thread covers just the basics of each method, and more research may be required for anyone looking into using one. Method 1: Pothos Pothos is a hardy plant that can use nitrates from aquarium water to help it grow. It can be placed in a sump, or in a container, which is then placed in the aquarium. The pothos should be placed in an area with good enough flow for it to reduce as much nitrate as possible. Depending on the size of the tank, pothos can reduce up to 10ppm of nitrate per week. This may not sound like a lot, but it can be enough to delay a water change by a couple days. Pothos is budget friendly, as a 6" pot can be bought at Home Depot for $15. A grow light can be used, but it's not necessary. Pothos does well with normal aquarium lighting or sunlight. Cost: 1 Effectiveness: 2 Reliability: 5 Method 2: DIY Algae Scrubber Algae Scrubbers that are sold commercially can go for hundreds of dollars, but the DIY method gives the same results for a fraction of the price. Algae scrubbers can usually only be used in sumps, as they have to be completely submerged. To create an algae scrubber, knitting mesh is placed in a high flow area of the sump, and a grow light is placed near the mesh. Algae will soon grow on the knitting mesh, and the water will be forced to flow through it. Just like pothos, the algae will remove nitrates, except much more effectively. The total cost of the materials, including the light, is about $40. Depending on the size of the scrubber and tank, the scrubber can completely remove nitrates, leaving them at 0. Cost: 2 Effectiveness: 4 Reliability: 5 Method 3: Anaerobic Nitrate Filter This method involves a filter that uses anaerobic bacteria to covert nitrate to nitrogen gas. Commercially sold units can sell for up to $350, and they aren't effective for larger tanks, but just like algae scrubbers, nitrate filters can be made at home. Large diameter PVC pipe, end caps, 1/2" tubing, a low flow pump, foam, and pumice will be needed to create the filter. The parts will cost about $50-75 in total. The bacteria in the filter require low flow, as they are anaerobic, meaning they thrive in low oxygen environment. The pump used should be 50gph or less. 30-40gph is best. Low flow allows oxygen to leave the water. Pumice creates the low oxygen environment for the bacteria, as it is extremely porous, and the center of each piece has very little to no oxygen. About 100 ml of pumice should be used for every 10 gallons of water, or 1 gallon of pumice for every 300 gallons of water. The bacteria should start to colonize in the filter after 4-6 weeks, although products like Prodibio Biodigest can speed up the process. This filter can reduce the nitrates to 0, and can keep them consistently at 0. To create the filter, a cap should be placed on one end of the PVC, and glued on. Next, a hole should be drilled for the tubing. After that, 3-6 layers of foam is placed inside of the PVC, as small debris need to be removed before the water reaches the media. The rest of the PVC should be filled with pumice. Next, the PVC is capped off with another drilled cap. 5-10 feet of tubing should be placed in each end of the filter, and the tubing on the side of the filter with the foam should be placed on the pump. The water should go through the foam first. Once the pump is attached, it should be placed into the aquarium, and the other end of the tubing should be put in the tank as well. Once turned on, the filter should begin to function like a canister filter. The pump is the intake for the filter, and the tubing on the opposite side is the outtake. Cost: 3 Effectiveness: 5 Reliability: 5 Method 4: Nitrate Reactor This method is very similar to the nitrate filter, and even uses the same bacteria to remove the nitrate, but there's one key difference. Nitrate reactors use a media called bio pellets, which provide a source of carbon for the bacteria to feed on. With a source of carbon to feed on, the bacteria can live in aerobic water, which is rich in oxygen. Since they are able to live in oxygen rich environments when introduced to carbon, a higher flow pump can be used, and therefore the nitrate reduction can happen at a faster rate. Another difference is that the media tumbles, which knocks the dead bacteria off, allowing room for new bacteria. The only downside is that the media has to be replaced every 6 months, because the bacteria feed on it, and the media slowly decreases in size. The bacteria will colonize the bio pellets in about 4-6 weeks, although products like Prodibio Biodigest will reduce the wait. The materials in total will cost $40-80, depending on how many bio pellets are needed. Although many companies sell nitrate reactors, it is, once again, cheaper to make your own. They are quite easy to assemble. Start with a bottle of any size, but preferably 500 ml or larger, and drill holes around the entire diameter of the bottle, near the bottom. The holes should create a circle around the bottle. After that, a hole should be drilled in the cap of the bottle just large enough for the pump outtake to fit in it. Next, the pump should be glued in place. Once the pump is secured, a piece of knitting mesh should be cut to the size of the bottle cap, and place on the inside. This will prevent the media from entering the pump when it's not running. After that, the bottle should be filled halfway with media. This should allow room for the media to tumble. Next, the bottle should be placed in the sump upside down, and the water should flow through the cap, and out of the holes near the bottom, now the top, of the bottle. Cost: 4 Effectiveness: 5 Reliability: 4 Overall, I recommend the anaerobic nitrate filter, as it reduces the nitrate to 0, consistantly keeps it at 0, and it doesn't require a sump, whereas some other methods require a sump.