Nitrate reduction (carbon dosing) for freshwater


I found this old thread that proves carbon dosing works somewhat for freshwater systems.

Sugar as a nitrate reducer | Sirdarksol 84119

Upon further reading about VSV (vodka-sugar-vinegar) dosing at, you can change or even eliminate the proportion of each ingredient based on what your tanks strain of denitrating bacteria likes to eat.

I don't do VSV but I use a bio pellet reactor which works wonderfully. I would probably get 80+ppm nitrates before each water change due to overstocking but I only get 10-20ppm before my weekly 20% WC. I tried Brightwell Aquatics Biofuel but noticed no significant change. I don't get bacteria blooms but instead get the occasional clumps that come out of the filter and return line. They either get eaten by fish or sucked in by the filter or end up in the refugium for the shrimps and snails to eat.

Also another old thread about a coil denitrator.

DIY Nitrate reducer | DIY - Do It Yourself 67424

Here's a non-DIY coil denitrator

I think the reason why some people fail reducing nitrates is that 1)they do not have enough (or the right strain) of denitrating bacteria, and 2)they lack the essential nutrients the bacteria need aside from a carbon source.

I use Seachem Stability and Brightwell Aquatics Microbacter7 as these have denitrating bacteria and are safe for freshwater systems. Both products are supplying my denitrating bacteria's population diversity. I dose once or twice a week rotating between products. In fact, my water gets clearer every time I dose.

I use RO/DI water for water changes since we do not like our tap. I replenish nutrients using salt mix(to 1.0025sg), calcium chloride, sodium bicarbonate, magnesium sulfate, Kent Freshwater Essential. Also an occasional dose of Tetra Pond Sludge Reducer for detritus management. I top off .5gal RO/DI water daily from evaporation. I have a bubble wall on the main tank and a Hofer Gurgle Buster aerates the refugium. A 300+GPH flow from the return line with an eductor takes care of water flow. The idea is to elevate nutrients for a complete and heathy microorganic ecosystem. I don't get it why they call some nitrate reducing systems "low nutrient". Wouldn't depriving any organism of essential nutrients kill it or make it sick?

Water Params:
Ammonia 0
Nitrite 0
Nitrate 20ppm (Phosban 150 NPX reactor)
Phosphate 0ppm (Phosban 150 GFO reactor)
pH 7.6 - 7.8
kH 8dKH
GH above 40dGH (stopped counting after 40 drops)
temp 78F

Stocking 60gal (excludes 10gal refugium):
9in common pleco (redecorates my aquarium and attacks my vacuum and garden tool with a head butt and tail whip; nobody touches his fake tree)
1 neon tetra and 2 cardinals (will not add these anymore since the F8s developed a taste for them)
2 glow light tetras (will not add these anymore for same reason)
4 marigold variatus platies (the one eyed male is my wifes favorite)
4 glass catfish (1 claimed the big house and wouldn't let anybody in including his buddies)
4 red minor tetra (doing their own thing)
6 dwarf puffers (they're all over everywhere; good camouflagers)
2 F8 puffers (masters of the universe, or tank)
5in BGK (voracious eater and growing fast)
6 bumblebee gobies (covert ninjas)
5 Balloon mollies (doing their own thing)
3 Sterba's cories (always out and about)
2 KuhlI loaches (hiding but comes out at feeding and lights out; lives in the other house and shares space with the BGK)
2 GBR (seems to have a grudge against everyone)
2 3in Angel fish (thriving and growing)
11 rummynose tetras (thriving and seems to have a peace treaty with the F8s)
2 female and 1 male guppies (hitchhikers from feeder GS)
Ghost shrimp, pond snails, and ramshorn in the refugium.

Feeding once daily:
2 cubes HikarI frozen bloodworms
2 cubes HikarI frozen mysis shrimp
1 cube HikarI frozen brine shrimp with spirulina
6 drops Boyd Freshwater Vita-Chem
Frozen food is soaked in Garlic Guard to thaw in a medicine bottle floating in the tank
3 pinches Aqueon flakes
60 live Ghost shrimps and 16 live pea sized snails restocked every 1-2 weeks for the F8s.

Has anyone else here been successful or have tried reducing nitrates aside from water changes?


HI matsungit,
Thanks for the write-up on your Freshwater carbon dosing. Interesting reading


Switching works! I just finished my last dose of Stability and the reading was between 10 to 20. After 2 days of the initial dose of Microbacter7 the nitrate dropped to 5-10ppm. I also noticed a sudden buildup of gunk in my biopellet reactor.

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