In saltwater aquariums, nitrate levels below 20 mg/l are recommended, and when caring for stony corals, below 10 mg/l. LPS corals tend to tolerate slightly higher levels, while SPS corals can tolerate slightly lower levels (<5 mg/l).

Below we give you 7 tips on how you can lower the nitrate level in your aquarium:

#1 Regular water changes

Logically, with weekly partial water changes you reduce the amount of dissolved nutrients in the aquarium. It is also advisable to use a suction cup to remove precipitation and deposits from the substrate every now and then during the water change. This prevents unwanted deposits from forming. Don't forget to clean your technical tank regularly and remove unsightly sludge build-up. Be sure to use osmosis water to prepare salt water and refill evaporated aquarium water, as nitrate levels in drinking water can be very high depending on the region (Rostock e.g. 4.5 mg/l, Dortmund 13.4 mg/l...).

#2 Feed less

Of course, you don't want your reef dwellers to starve, but if the nutrient levels are too high, it might be worth considering reducing the amount of food. Frozen food should generally be rinsed. It's better to feed small portions several times a day than one large meal.

#3 Reduce fish density

Lots of fish = lots of hunger = lots of food = high nutrient load. A high fish population, especially with active swimmers (which need a lot of energy), has a direct impact on water quality. One option is to reduce the fish density (or move them to a larger aquarium?).

#4 Use more consumers

Consumers such as corals and macro algae take nutrients from the water to grow. So feel free to use more of them! Another idea is to install an algae refugium in the sump. Use fast-growing species such as green algae.

#5 Filter performance

Clean mechanical filters such as fleece filters and filter socks regularly and check the function of the skimmer. Good filtering means that waste materials are removed early enough and the nutrients they contain do not dissolve in the first place. Deni-filters (nitrate filters or denitrification filters) can be purchased specifically for nitrate breakdown. In these, nitrate breakdown takes place with the addition of carbon in an anaerobic environment (without oxygen).

#6 Carbon dosing

Adding carbon will stimulate bacterial growth in your tank. In addition to a carbon source, bacteria also need phosphorus and nitrogen to grow. That's why they absorb the phosphate and nitrate present in your aquarium water. Possible ways of dosing carbon include the vodka method (cheap and effective) or using commercial products such as Tropic Marin Elimi-Phos (safer to use). Adding a carbon source can cause serious problems if overdosed. Before using the vodka method, you should therefore find out the details and dosage.

#7 Tropic Marin Reef-Active

Reef Actif contains marine biopolymers of natural origin. Biopolymers are long-chain molecules that are able to bind other substances, such as nutrients, pollutants or turbidity. These substances are only released again after the biopolymers have been broken down. Since the polymers can be used almost exclusively by symbiotic bacteria in corals, sponges and other filter feeders, the nutrients end up exactly where they are needed via this detour.

By the way: exceptions prove the rule. There are also coral systems that are successfully operated with relatively high nutrient levels. So always keep an eye on your corals - if they look healthy and happy, then they are.