how can I reduce nitrate in freshwater aquariums?

Question

I have a 30 gallon freshwarter tank with 2 plecos. I have tried all I can think of to reduce the nitrate and I'm not able to. The water I use during water changes has a trace amount and I'm adding nitraban to it. I had a gourami's and platy's with the plecos and they did fine and suddenly died. I figure the high nitrate level is the reason my fish are dying. What else can I do? I've even added r/o water. I have a lot of little snails, could they be the culprit? Plants don't do well, they wind up getting eaten.
HELP

Answer 1

The best conditioner I've used is Prime, it zaps ammonia and nitrate extremely well. Other considerations on a freshwater tank: do you have too many fish? Plecos are nice to remove the unsightly waste but the nitrogen will still be there. No more than one inch of fish per gallon of water in the tank. Mindful that many mollies are 1.5 to 2 inches, you should really have no more than about 15 smaller fish in that size of tank. If so you will need a tremendous amount of biological and mechanical filtration.

Keep it simple, go with fewer fish, regular water changes using a good conditioner like Prime. Also consider diseases as the cause. Unhealthy fish die rapidly from nitrate toxicity. Otherwise healthy fish can tolerate fairly high amounts, prime example goldfish. So, recommend only adding a few fish at a time, acclimate them slowly, and watch for signs of illness: rapid breathing, poor color, noticeable splotches or spots.

Also, people walk by their tanks and think, "oh, they look hungry, let me feed them" because fish are people watching. Only feed small amounts 2-3 times per day max. No more food than what can be consumed in a 3 min timespan.

Be sure to change out filters regularly and add new carbon. Many people get apathetic with the hardware and overlook it when the tank is having problems.

My tank: 150 gallon saltwater reef, hard corals, soft corals, invertebrates, fish, megaflow 4 sump, berlin skimmer, chiller, 72 inch hamilton halide and pc combo, uv sterilizer.

Answer 2

Try changing your filter?? I would much prefer to have high nitrates than cycling problems! Please don't touch your filter, it's generating a lot of nitrates because there is a lot of ammonia/waste being produced/introduced in the tank. Your biological filter is not the problem! If it's dirty and due for a cleaning sure, but no more than rinse the media in tank water to preserve the bacteria.

True plants help a tremendous amount, try floating plants such as hornwart and frogbit if you're having problems with other aquatic plants. By breaching the surface these plants consume CO2 from the air and are able to do far better in a tank that is less suitable for aquatic plants. Only some snails really harm plants, most eat plants only once their tissues have softened due to other problems. But snails do add to the overall bio-load of the tank and generally speaking, most nitrate problems are caused by overstocking or overfeeding.

Without knowing more about the tank, I'd say reduce feedings to once every other day and perform 20-30% weekly water changes. If you are able to test nitrates and find a concentration over 30-40ppm then more frequent changes would be required until the level is down below this range. There may also be eccess accumulation of waste in the gravel, which would require vacuming out, however without knowing more it's hard to say. If the plants are dying, remove them before they melt away as they too will add to the overall nitrate concentration.

Hope that helps

Answer 3

Nitrate is a chemical created by the bacteria in your filter after the bacteria processes amonia from animal (fish n snail) waste. Try changing your filter and doing 25% water changes once a week. The 2 plecos (depending on their size) could be too much for the tank. A 30 gallon is too small for 1 full grown pleco. Reduce the amount you are feeding the fish. When the nitrate levels go down add plants to the tank. Live plants are really the only natural thing to reduce nitrates. Even a half eaten plant will reduce more nitrate than no plant at all.

Answer 4

Your plecos are the problem with your plants and nitrates. They poop a lot and eat plants. The tiny snails shouldn't be a problem in an otherwise healthy tank.

Plecos can grow over 2 feet and should be in only the largest of tanks ( >150gal ), and they can cause havoc in anything smaller with the surprising amount of waste they generate as they grow.

Do water changes of 30% two or three times a week to get rid of the nitrates, if your tap water reads over 10 ppm find another source ( not r/o as it doesn't have enough minerals ) and find a new home for the plecos. Carefully feeding the fish so that there is no leftovers after 30 sec. is necessary in preventing nitrate and waste buildup as well.

Answer 5

How long are the plecos? If they're more than 7 inches long, they might be the culprits themselves.

The snails are not the problem, they are merely a sign of the problem. The problem is overfeeding. You need to put less food in the tank. Food gets eaten, either by fish, or by snails, or by bacteria, and that turns into nitrates. Lots of snails indicates lots of food to support them.

You can kill the snails, and then they won't eat the plants, but plecos also like to eat some plants. Floating plants would be harder for a pleco to eat, and easier to throw out once they've absorbed nitrates and are covering the top of the water. Frogbit and hornwort are two. Duckweed, and fairy moss are two others. However, these are all very small, and can gum things up Buttefly fern is a little bit bigger, but requires lots of light to grow the right size. Water lettuce and water hyacinth are much larger, but will require you to keep the water level lower, and might get munched on.

When using floating plants, it is best to prop up one side of the aquarium cover, so that the water that condenses on the lid will not drip back on the plants. It will also be important to keep the filter outlet below the water level, so it doesn't splash on the plants.

Charcoal, and zeolite can help to keep nitrate levels down between water changes, but they themselves must be changed at proper intervals as well, and may interfere with medications.

Answer 6

How high are your nitrates? Fish can easily tolerate up to 40ppm.
Plants are likely being eaten by the snails - remove the snails, just squish them, or leave piece of zucchini overnight and remove the snails that are eating it the next morning.
Are you fish getting adequate light/fertilization? If not, get some fertilizer for them (trace elements, macro/micro) - healthy plants will lower nitrites and help keep nitrates in check.

How often do you do water changes? 30% per week is recommended, but you could do 10-20% every few days until the nitrates go down.

I don't suggest you use chemicals like nitraban. They are usually ineffective and cause more harm than good.

If your nitrates ARE higher than 40ppm, you may 'old tank syndrome'. It may be time to replace some of the gravel or the filter cartridge.

You may be a little overstocked with the two plecos. Commons can grow to 12-24". Even bushy-nosed plecos grow to 5-6" and even one is cramped in a 30 gal. Maybe this is a good excuse to upgrade to a bigger tank? :)

Answer 7

There should be no reason to have high nitrates if you are using R/O or distilled water for your changes.

If you have high nitrates using either of those then you are seriously over feeding your fish.

Make sure to feed at most 2 times per day and only what they will eat in 20-30 seconds with no food left over in the tank.

Water changes are typically used to lower nitrates, but live plants can also be used to lower nitrate levels in a tank.

Answer 8

Water changes and live plants will help lower your nitrates. I would suggest any of the hygrophilia or the cryptocorns. Make sure you select plants that can survive with the type of fish you keep. if the pleco's seem to be the culprit i would suggest feeding them some Zucchini at night (tie off a slice to a rock with an elastic band.)

Answer 9

Rotting plants, large fish, snails all these things are contributing to the high nitrates.
Remove the snails,
increase the light on the tank to encourage your plants and algae, plants and algae feed on the nitrates.
Reduce your feeding of the plecs and clean the filter of detritous regulary.
Do 25% water changes twice a week for a month check your nitrates and they should be going down if you do all this.

Answer 10

If a tank has high nitrates that are continually high even after water changes then the tank is overstocked. I reccommend either getting a new tank or getting rid of some fish.