Carbon dosing = 50 no3 & 0 po4 - what now?

[rocknut]

Hello everyone,

So I started dosing Red Sea NoPox to my 150 gallon system 11 days ago, after coming to the conclusion (through another thread here on Reef2Reef) that my tank was too limited in carbon to process the high NO3 levels in my tank. When I started, my po4 was between 0.03 and 0.04 without running any GFO. My NO3 however was right around 100, per my Red Sea and Salifert test kits.

I started dosing NoPox with a roughly half dose of 10ml/day (recommended dose would have been 18 ml/day), which I bumped up to 12 ml/day on Tuesday. Noticed the telltale filter sock clogging, and white bacterial film on the sump walls, but no other ill effects. Did notice my few SPS corals starting to pale yesterday, and confirmed that although my NO3 had in fact dropped down to 50, my PO4 is zero with my Hanna ULR meter. Per the Red Sea instructions, I cut my dose by 50% tonight, down to 6 ml/day.

I'm worried that zero PO4 is going to be a problem, but am also encouraged that my NO3 numbers have started to drop. Any suggestions on a plan going forward? I hate to cut the NoPox back too far as it is definitely working on my NO3, but know that zero PO4 throws the ratio off, and I'm assuming the NoPox will not be able to continue lowering NO3 without any PO4 left to feed on.

Thanks in advance.

Rocky

 

[Rob Lion]

you are correct @rocknut , you will need phosphates / nitrates / carbon in the redfield ratio of 1 / 16 / 106 to remove the nutrients though carbon dosing.

I use NOPOX as well..... the key is to make sure your skimmer is removing the bacteria etc so it doesn't film else where, personally i run 24/7 without filter socks, I only put one in when in doing a deep clean of the substrate/rocks.

if you aim for 0.015 ppm Phosphates = 0.2 ppm Nitrates (0.015 x 16)

If you are running any type of GFO / RowaPhos etc, stop.

Don't forget, you are testing the free phosphates in the water column, there are still Phosphates bound into rocks and organic material that will be still available. If you have algae growth it means you have N and P.

Water changes are probably the best and easiest way to reduce your nitrates at this point.... feed less, put a clean filter sock in, blow off all rocks and depending on the type of sand bed you have, gently stir the sand if it is 1" or less to release and trapped detritus there, remove the filter sock.

Once you are balanced at P:N at 1:16, dose the minimal amount of NOPOX to keep at those numbers, it is easier and better to start doing low and building up, than dosing to high and reducing, you can run GFO etc to sustain a lower P if needed.

Caution, do not rapidly change carbon dosing.... increase/decrease slowly.

 

[rocknut]

you are correct @rocknut , you will need phosphates / nitrates / carbon in the redfield ratio of 1 / 16 / 106 to remove the nutrients though carbon dosing.

I use NOPOX as well..... the key is to make sure your skimmer is removing the bacteria etc so it doesn't film else where, personally i run 24/7 without filter socks, I only put one in when in doing a deep clean of the substrate/rocks.

if you aim for 0.015 ppm Phosphates = 0.2 ppm Nitrates (0.015 x 16)

If you are running any type of GFO / RowaPhos etc, stop.

Don't forget, you are testing the free phosphates in the water column, there are still Phosphates bound into rocks and organic material that will be still available. If you have algae growth it means you have N and P.

Water changes are probably the best and easiest way to reduce your nitrates at this point.... feed less, put a clean filter sock in, blow off all rocks and depending on the type of sand bed you have, gently stir the sand if it is 1" or less to release and trapped detritus there, remove the filter sock.

Once you are balanced at P:N at 1:16, dose the minimal amount of NOPOX to keep at those numbers, it is easier and better to start doing low and building up, than dosing to high and reducing, you can run GFO etc to sustain a lower P if needed.

Caution, do not rapidly change carbon dosing.... increase/decrease slowly.

Thanks Rob. So, I actually started dosing the NoPox as the result of another thread I started a few weeks ago on this forum. In a nutshell, I rebooted my tank in April with 150 pounds of high quality aquacultured live rock, and although I hadn't added any fish as of when I started the thread, had about 100 no3. It was the consensus that my system was just very carbon limited because I had everything needed in place (good skimmer, lots of flow, doing water changes, etc), so I decided to start dosing Nopox.

I am going to continue doing water changes, but wonder if I should be doing anything right now to get some PO4 back into my tank? I only have four SPS corals now, and two fish, as I have been stocking very slowly, so bio load is very light.

Thanks again for all of your useful suggestions, and advice!

 

[Kungpaoshizi]

Add food that has Ash listed in content..(iirc that's basically phosphate)

 

[Rob Lion]

good luck @rocknut , don't worry, my first ever tank had nitrates of 180!! i had put in 3 large deli prawns and left them too long.... I also added all sorts of food stuff into it when cycling because my seneye reef wasn't working right...phosphates were low, like 0.02 doh! That's when I learned about NOPOX too... and its limits!

personally, any normal food you add will likely add more nitrates than phosphates, although dry food like fish flake less so ..... personally, just dose NOPOX at the lower limits (1ml per 25gallon) if you're getting too much browning of corals and/or white bacteria sticking in places your skimmer can't keep up with..... ideally, your skimate will look like a cup of tea, a sort of light tan colour... and your skimmer will go crazy...... make sure you are WET skimming too! and do as many water changes you can bear... just buy in some cheap salt for that, don't waste money using the good stuff.....

by limiting feeding, keeping everything clean etc, it will probably take you about 2 months to get the system sorted and balanced that way, that's what it took me.... :/

If there is a quicker way, hopefully someone here will know about an easy way to dose phosphate somehow.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, carbon dosing seems to reduce nitrate a lot more than one expects from the Redfield ratio because denitrification uses nitrate and not phosphate.

If you do find the nitrate stops declining, you can look to dose some phosphate. There are a variety of hobby and DIY products that work well.

 

[rocknut]

Add food that has Ash listed in content..(iirc that's basically phosphate)

Thanks for the info, Kungpaoshizi. Didn't realize that about ash, so good to know!

 

[rocknut]

good luck @rocknut , don't worry, my first ever tank had nitrates of 180!! i had put in 3 large deli prawns and left them too long.... I also added all sorts of food stuff into it when cycling because my seneye reef wasn't working right...phosphates were low, like 0.02 doh! That's when I learned about NOPOX too... and its limits!

personally, any normal food you add will likely add more nitrates than phosphates, although dry food like fish flake less so ..... personally, just dose NOPOX at the lower limits (1ml per 25gallon) if you're getting too much browning of corals and/or white bacteria sticking in places your skimmer can't keep up with..... ideally, your skimate will look like a cup of tea, a sort of light tan colour... and your skimmer will go crazy...... make sure you are WET skimming too! and do as many water changes you can bear... just buy in some cheap salt for that, don't waste money using the good stuff.....

by limiting feeding, keeping everything clean etc, it will probably take you about 2 months to get the system sorted and balanced that way, that's what it took me.... :/

If there is a quicker way, hopefully someone here will know about an easy way to dose phosphate somehow.

Thanks again, Rob. Skimmer is definitely skimming wet, and I am getting a nice bronze/brown tea colored skimmate, with some nice "floaties" at the bottom. I'm someone that has used lots of skimmers in the past, and never think they are doing "enough", but my current skimmer (30" Lifereef) seems to do a good job either skimming dry or wet.

Also had come to the same conclusion regarding bumping up the water changes, and I am going to do 20 gallon changes with Reef Crystals daily for the next four days. I know it would be better to do one 80 gallon change, but don't have a large enough mixing tank to easily do that.

I also bought a Jaboe 2,000 gph power head and stuck it in my coast to coast overflow, to keep any detritus from settling in there (the coast to coast runs the entire five foot length of my tank).

 

[rocknut]

FWIW, carbon dosing seems to reduce nitrate a lot more than one expects from the Redfield ratio because denitrification uses nitrate and not phosphate.

If you do find the nitrate stops declining, you can look to dose some phosphate. There are a variety of hobby and DIY products that work well.

Thanks, Randy. I actually did add a small amount of a Phosphorus supplement (much less than recommended) and my po4 tested at 5 ppb using the Hanna ULR tester. Figure that if I can keep this in the 5-10 ppb range, the Nopox should be able to keep knocking the NO3 level down. Plan to test the PO4 levels daily for a while to make sure they don't bottom out, or go too high.

 

[TherealplexiG]

but my current skimmer (30" Lifereef)

Sorry off the topic a little bit, what pump are you running on Lifereef, I have heard that people running DC pumps these days with Lifereef??

 

[rocknut]

Sorry off the topic a little bit, what pump are you running on Lifereef, I have heard that people running DC pumps these days with Lifereef??

@TherealplexiG After doing a lot of reading, I went with the Fluval Sea SP4, which is rated at 1,822 gph. Also dead silent and doesn't put out the heat of the Mag pumps.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks, Randy. I actually did add a small amount of a Phosphorus supplement (much less than recommended) and my po4 tested at 5 ppb using the Hanna ULR tester. Figure that if I can keep this in the 5-10 ppb range, the Nopox should be able to keep knocking the NO3 level down. Plan to test the PO4 levels daily for a while to make sure they don't bottom out, or go too high.

Yes, that sounds good.

Happy Reefing.

 

[zangmann]

@rocknut Any updates?

 

[rocknut]

@rocknut Any updates?

Thanks for the interest, I was thinking I needed to update this:

So, taking the advice on this thread, I decided to hit the NO3 numbers with big(ish) water changes. I bought two 200 gallon boxes of Reef Crystals and did six, 40 gallon water changes over the course of 12 days. This alone brought my NO3 levels from around 50, where they were at the end of July, down to about 6, where they are now. I also had to dose 5ml of Brightwell Neophos several times, whenever my PO4 number would bottom out. This would raise the PO4 number up to about 0.02 or 0.03. Interesting observation: I figured out that I could almost guess the PO4 number just looking at my Jedi Mind Trick Montipora. If the coral greyed out, PO4 was at zero.

At this point, I have lowered my Red Sea NoPoX dose to 8 ml/day and my NO3 is holding at 5 or 6. LOTS of bacterial build up on the surface of the water in my sump, but nowhere in the display tank itself. If I dose any more than that, the sump gets really nasty.

At this point, I'm hoping that NO3 will maintain, or drop a little more, and that as my tank continues to mature, I can keep lowering, or even eliminate to NoPoX.