High Nitrates

Question
Greetings! My husband and I keep a freshwater aquarium that is 29 Gallons. We currently have 2 gourami's, 4 Tiger Barb, 2 small angel fish, and 1 pleco in the tank. We've had our tank for about 1 year now, until recently we had no problems whatsoever. About 4 months ago we added new fish to the tank (gourami's) and came down with Ick. (Lesson learned to get a quarantine tank). We treated the Ick, lost a lot of fish. We waited 1 month before adding any other new fish - this is when we got the sharks & barbs to replace the fish we had lost. Now, about 2 months now I have been a very difficult time managing the nitrates in the tank. They are extremely high. We use a carbon/biowheel filter & I change the carbon about every 2 weeks. I have been doing water changes every week... I started with 10% but as that wasnt working I increased to about 25-30% water change every week. I do use the gravel vacuum every week when doing the water changes. I don't overfeed the fish at all. Ive tried using the stress zyme made by API as 1 fellow recomended that too me. None of this has worked at all to fix the nitrates. The past 2 weeks they have been half of what they were previously but it's still insanely high. Everywhere I go and everyone I ask is completely stumped. I should also mention I tested my tap water and its 0 nitrates after conditioning... any thoughts? suggestions?

Answer
Hi Genevieve,

Nitrates are the end stage of the nitrogen cycle. You start with ammonia, which gets converted to nitrites, and in turn the nitrites turn into nitrates. In a regular freshwater tank, the only thing that removes them from the water is water changes. In a planted tank, the plants suck up the nitrates - sometimes planted tank hobbyists need to add liquid nitrates to the water for the plants!

My suggestion to you would be to get some floating plants such as hornwort. Fast growing plants suck up the nitrates from the water quickly. Water lettuce and water hyacinth work beautifully in ponds, not so much in aquariums - and besides, they are invasive so not usually sold. You'll have to settle for things like hornwort, Indian fern and Amazon frogbit. Nothing much works better for removing nitrates out of the water! You could try nitrate absorbing resins (such as NitraZorb) but plants are the natural way to go, plus, fish love to hide in them. Especially top dwellers like gouramis.

My guess as to why your nitrates are high is that for the year your aquarium was running, you didn't do sufficient water changes. If you were doing only 10% per week, this isn't really enough to dilute nitrates. Eventually your nitrates will creep to 20 ppm, and that's when you should start getting bigger W/Cs in. Anything higher than 40 ppm can start causing trouble. Fish will not grow at the rate they should, and they might start losing their appetite and fading out in color. So be sure to do big water changes (25% weekly) and get some floating plants! Stress Zyme really won't help with your nitrate issues. Your tank already has plenty of bacteria (since ammonia and nitrites are 0 ppm) - it doesn't need more.

One thing that can help with high nitrates is to rinse your filters. If your filters are the cartridge kind, try rinsing them in aquarium water every week and continue replacing them twice monthly. Also, take the filter apart and clean any gunk that may be in there - this slows down the flow and can elevate nitrates. You can also rinse the bio-wheel in aquarium water (but not chlorinated tap water!)

As far as power filters go, my favorite is the AquaClear - the media is rinseable and reusable (saves $$). You don't even need to add carbon, the Biomax and foam sponges are all you need. Carbon takes any odors out of the aquarium water and also any yellowing. If you are replacing enough water weekly, you don't really need carbon, there will be very little odor or yellowing to begin with...your aquarium will do fine without it. It doesn't hurt, and can help a little, but it's not *essential* as you may have been told.

If you are just feeding flakes or pellets, the way most people do, try alternating with a "veggie" flake such as Spirulina flake or pellets, algae wafers or a low protein flake such as goldfish flake. Wardley founds are usually lower in protein. They aren't as high quality as other brands, such as Omega One, but they don't cloud the water because they have lots of vegetable based fillers. They are good to use a couple times a week, along with algae wafers. You can also try taking a frozen, defrosted pea and squeezing the innards out of it. Most fish love it! The skin doesn't break down and will stay in your tank, which is why you ought to pinch it off beforehand.

I hope that helps! Take care.
Nicole