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FAQs on Marine Freshwater Quality involving Nitrates: Chemical/Physical Filtration

Related Articles: Nitrates in Freshwater Aquariums, Establishing Cycling, Freshwater Filtration, Know Your Filter Media, A Concise Guide to Your Options by Neale Monks, Setting up a Freshwater Aquarium, Tips for BeginnersWater Quality and Freshwater Aquariums

Related FAQs: Nitrates 1, Nitrates 2, & FAQs on FW Nitrates: Importance, Science, Measure, Sources, Control, Troubleshooting/Fixing, & Ammonia, FW Nitrites, Biological Filtration, Freshwater Nutrient Cycling, Establishing Cycling 1,

There are some products that work short term (neutralize the NO3 present) and some that go on possibly to spur nitrification long-term. There are also some notorious "phony" cures.
Carbon won't remove

Nitrite levels waaaaaaaaay high - ugh.  9/2/07 Neale, <Kristi,> OK - now I'm thoroughly confused. <Pray tell...> Regarding my nitrite levels - they were and still are reading 2.0 mg/L. I double checked the color card (API test) and that's what it is and has been. <OK. Well, not actually OK, but OK as in I understand.> Other levels are as follows: Nitrate ~10 mg/l (and on its way down), ammonia 0, ph consistent at ~ 7.7. <These are fine.> Given that 1 m/mg./l nitrite is lethal and my fish are still alive, what is going on? The 35% water change yesterday didn't do a thing to reduce the nitrite 2.0 levels. The test kit suggests the following actions when initial levels are high: <1 mg/l is a ball-park figure. It varies. 0.2 mg/l will kill Tanganyikan cichlids pretty quickly, while mudskippers (adapted to resting in burrows when the tide is out) will take levels of ammonia and nitrite much higher than most fishes. So it varies. What nitrite does is stress the fish, damaging tissues and messing up its immune system. In the long term, a tank maintained at 2 mg/l nitrite is unhealthy, and the mortality of the fish will be high.> 1. Add a Nitra-Zorb to the filter, <Waste of time.> 2. Add bacterial supplement to help speed the development of the bio filter, <Waste of money, except perhaps in the case of BioSpira and Tetra Safe Start, which are "live" bacteria cultures. By contrast, filter-boosters and filter-aids have had very mixed reviews from aquarists, and are probably not all that useful.> and 2. Add aquarium salt to reduce nitrite toxicity to fish while the natural filter is removing the nitrite. <Possibly an option. The livebearers and glassfish obviously won't mind this at all.> Question: Is adding *any* salt a good idea given I have an ADF and dwarf Gourami? If so, at what dose? <It's a case of "less of two evils". As a short-term supportive, salt has some value here. You don't need Aquarium Salt for this, plain non-iodized cooking salt will do just fine (this is sometimes sold as Sea Salt for example). Use small amounts at first, perhaps 1 gramme per litre. If the fish are basically fine, I'd back off using salt, and just cut back the food and let the filter develop speedily. Regular water changes will dilute the nitrite enough to keep the fish healthy, all things being equal. This is "cycling with fish" basically, and done properly, works fine. It's the old fashioned approach to be sure, and done badly ends up with a lot of dead fish, which is why so many books recommend fish-less cycling instead.> What could be causing such high nitrite levels? <It would appear that your nitrifying (ammonia -> nitrite) bacteria are all in good shape, but the nitrifying (nitrite -> nitrate) bacteria are for some reason not doing their job. Give it 2-3 weeks more and you should be fine. In the meantime, do everything you can to optimise conditions for the fish and the bacteria. You already have an alkaline pH and fairly high hardness, which is what the filter bacteria like (they HATE soft/acid water!) but they also need lots of oxygen, so check circulation of the water is adequate. Also make sure the filter is sufficiently large, and not filled with worthless rubbish like carbon. What you want is plenty of good quality biological filter media. Sponge and ceramic hoops are best, but filter wool will do too. Make sure the media aren't clogged up.> Kristi <Hope this helps, Neale>

AZNO3 in freshwater aquarium  2/19/07 Bob, can AZNO3 be used in a fresh water aquarium without a protein skimmer to reduce nitrates? Thanks Bob P. <Mmm, can be used... ( http://www.marinedepot.com/aquarium_additives_azno3.asp?CartId=)no need to use a protein skimmer in/with FW systems (are problematical due to physical/chemical properties of phobic molecules in such)... but there are many other "more dependable" means of nitrate reduction... in FW... covered on WWM. If you purchase this fine product, make sure it is "fresh" and store in a fridge... and use w/in two months... Bob Fenner>

High nitrates after 4 months!  - 5/2/2006 <Hi, Christine. Tom with you.>> I've had my 30 gallon tank set up for 4 months. I did the fishless cycle and all the levels were great! <<Kudos to you and more kudos!>> I added fish and it all came undone. <<Eeek! What happened?>> 6 African Cichlids <Cichlids>> live in the tank with a coral substrate, plastic plants and a 300 GPM waterfall filter. <<Uh, oh. Too many of this species for a 30-gallon tank.>> The nitrates are over 40 ppm no matter what I do or how often I do it.  Fish are very healthy....growing like bad weeds and everyone gets along as much as cichlids are able to get along. <<Did you research these fish, Christine? (More to follow...)>> I've tried adding carbon to the filter media, <<Won't do it...>> weekly 40% H2O changes, vacuuming more often. <<Very good practice. Hoping you're vacuuming deeply (all the way to the bottom) and not just "superficially".>> What have I missed? <<You have too many of these fish in the size tank that you have. Your filtration is likely undersized for the situation. You don't mention how much you feed, or what you feed them but, they can be "messy". Uneaten food/detritus will contribute to nitrate levels.>> Does it really matter anymore if they are healthy that the nitrates are high. <<You REALLY need to research your fish, Christine. High nitrate levels can lead to HITH/HLLE disease in Cichlids. Your "target" should be less than 20 ppm. With Cichlids, I would aim for < 5 ppm to be on the safe side. (Side note: Unless you have Dwarfs (and they aren't if they're African, i.e. Malawi, Tanganyika, Victoria), you'll need a larger tank in the future.)>> The other chemical levels are well within normal parameters; ammonia is nonexistent, no nitrites and I have hard water. <<All here is very good, Christine.>> Thank you in advance for your help Christine <<You're welcome. Tom>>

Re: New Tank Woes  9/29/05 Thanks again Catherine.  The two neon Gouramis look like they will be dead by morning.  <Give them a chance.>  The 3 zebras, 1 molly and dwarf Gourami that are left still look pretty good.  The molly and zebras had spots, but they appear to be gone.  <Keep the salt in the tank for 3 weeks as well as the elevated temperature.>  Wal-Mart suggested I buy Tetra Easy Balance with "nitrate reduction granules and pH stabilizer".  Should I use this and continue with the tap water.  <I had some luck with Nitra-Zorb by Aquarium Pharmaceuticals.  Nitrates are hard to get rid of.>  I am worried about matching temperatures, etc. if I buy distilled water.  <Just put it on the stove for a minute or two, or if your room temperature is warm, you should be okay to add it if you are only doing 10% changes.>  This has been a great learning experience for me.  <Check out the WetWebMedia Chatforum for even more information.>  Your website is great.  Again, thank you for your time and help.  <Good luck!>

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