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Old 01/15/2019, 08:48 AM   #1
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Join Date: Feb 2016
Location: England, Earl Shilton
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How to reduce nitrates


I already know some of the answers I'm going to get...... BUT

I do like to feed my tank regularly (3-4 times a day) with a mixture of frozen pellet and live foods.

I'm happy with my phosphates at 0.06, I have no algae problems so not looking to use anything thats going to affect my phosphates to much.

I want to start keeping the more delicate sps. My nitrates are at 25ppm and I tried a Tenuis and it RTN 'd within a few days.

I'm thinking bio pellets?

If in doubt ask!
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Old 01/15/2019, 09:26 AM   #2
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Just about all carbon dosing processes, including biopellets, will reduce phosphates also. Not nearly as the nitrates though. If your system truly maintains .06 ppm of phosphate without assistance right now, you could end up with 0 phosphate if you carbon dose. When that happens, nitrates will not be reduced very effectively because phosphate is required for the process to work.

That said, IMO, any phosphate level above 0 indicates that there is enough phosphate in the system. The actual number isn't important. You have room for some reduction as long as the level remains above 0.

Few things address nitrate without affecting phosphate. Matrix blocks can provide more surface area for biological filtration that would address nitrate if placed in very low flow areas. Same goes for adding rubble rock in a low flow area. Various "denitrators" can do the trick. I don't have any experience with them, but many use sulfur denitrators.


Current Tank Info: In-process, 90 Gallon SPS Reef
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Old 01/15/2019, 10:48 AM   #3
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Originally Posted by fishkeeprian View Post
I'm thinking bio pellets?
I will recommend liquid carbon dosing over biopellets anyday..
Its just so much easier/more effective/faster acting and cheaper,etc...
No need for a pump running 24x7.. No clogging issues,etc...
Simply a bottle of distilled vinegar and a dosing pump and you are done..

For me carbon dosing is only required when a tank is new (usually dose carbon for about the first year or so) until a sufficient bacterial colony is established then I take it offline and the tank handles its own..

Who me?
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Old 01/15/2019, 03:30 PM   #4
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To start with, RTN has nothing to do with no3. With enought light and flow, no3 at 25ppm and 0.60ppm po4 sps can flourish too. Infact i wanted to raise my parameter to yours as mine has zero no3 and caused imbalance.

Stable parameter is important than chasing numbers

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Old 01/15/2019, 10:35 PM   #5
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Nopox works great but it will reduce your phosphates. Since you are feeding a lot, the phosphates will be in the water no matter what the reading is.

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Old 01/16/2019, 03:35 AM   #6
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I had nitrates for years at 40-50 ppm. Tried Nopox, vinegar dosing and it didn't work for me. Finally ran bio pellets for 5 months till i got under 20 ppm. Didn't do much for my phosphates though. When my nitrates hit about 12 ppm I stopped the pellets and now set up reactor for macroalgae. Nitrates are at 8 ppm but still struggling with high phosphates even running some GFO .

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Old 01/16/2019, 04:06 PM   #7
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To reduce nitrates in my 60g hexagon. i made my own little canisters.. connected to a old eheim pond pump i had from watercooling my pc back in the day. I filled both canisters with denitrate and matrix (one has rings because i ran out of denitrate).. its about 4 liters worth.. Put the inlet and outlet hoses in the tank the inlet has a sponge prefilter on it so stuff doesnt get in the canisters.. And within 2 weeks my nitrates went from 40ppm to 0-10 depending how much i feed.

I never have to do water changes if i didnt want too. Flow btw has to be low.. mine is at about 40gph.. The pump is a eheim 1048 rated for 148gph. But due to water being pushed through canisters packed with media it it slows it to about 40 which is the perfect speed for anerobic bacteria to grow.. I dont need to do any dosing of vodka or what not

Yea it looks ghetto but i dont care.. it works. I originally had it on my 135g tank, it kept nitrates at around 20ppm.. now that i took it off my discus tank for my salt water tank nitrates creep up to the 40's before i do water changes. And my discus i feed 4x a day with a crap load of food 3 cubes of beef heart and huge pinches of flakes.. But thats ok its cheaper to change 80 gallons of fresh water weekly then changing 30 gallons of salt water in my 60g hexagon every week due to nitrates rising no more wasting salt and stressing out corals and fish

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Old 01/16/2019, 08:18 PM   #8
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I use NoPox, have for quite some time, when the tank was new I brought nitrates down to 2-3ppm from 40ppm but it took a couple of months.

Two years later I continue to use NoPox to maintain 2-3ppm but with a much smaller dose.
NoPox will work but takes time for the bacteria to reach required levels

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