Dosing causing rise in Phospates, GFO?

[Bossman]

I've been dosing NOpox to reduce high nitrates (50+) and after some time they have come down to approximately 3. This has taken several months of dosing, checking levels, adjust dosing, etc. When the nitrates were high my phosphate levels were almost undetectable with Hanna ULR. Now that Nitrates are down to low single digits phospates are rising, today .54.

Should I run GFO to lower Phospates? Some threads I have read are all about using GFO. But some threads advise not to use GFO?? I have adjusted the NOpox dose to keep the nitrates low but just unsure where to go now.

I did do a 50% WC today which will bring them down somewhat.

 

[Spare time]

If you do just make sure you use a small amount. Nopox wont bring phosphates down to ultra low levels in some cases. I did both but would get weird slime probably from a lack microdiversity due to ultra low nitrate and phosphate

 

[Idoc]

So many threads with problems after using GFO. Too quick of a decrease seems to throw the balance off and then come the dinos!

The couple of times I needed to slightly reduce Po4, I put a small amount of Phosguard in a bag and tossed it in a high flow area of the sump. Then slowly watched the Po4 chine down gradually over a week or longer.

 

[Bossman]

I have used GFO before this way and it seems to work slowly. I don't have a reactor. It seems there is a balancing issue with nitrates and P03. Just want to make sure I'm on the right track. I hear some like to remove almost all nutrients and add them back in to feed the coral/fish.

 

[SPR1968]

Nopox is very good at reducing nitrate, but not very good at phosphate and depending on the system, if you don’t do something else, phosphate will increases like you’ve found. You also need to ‘wet skim’ with Nopox. I always find when phosphate is high, the skim is a green colour, your looking for a ‘weak tea’ colour

I run Rhowaphos 24/7 in a reactor and this keeps phosphate locked down very low with a target around 0.03 but if my Hanna says 0 then I’m happy do to test error margin. I now it won’t really be 0 because of the massive bio load I have.

If you do add GFO maybe start slowly so you don’t upset any corals if they’ve got used to it, but it will need changing regularly to start (like every few days/week) as it becomes spent or it won’t work. I change the rhowaphos every 3-4 weeks now, and this is the best single thing I ever added to my system.

So despite what Red Sea say, you can run them alongside each other, and many including myself do.

I also wouldn’t do 50% water changes, unless you have good reason, or your just going to keep throwing the water chemistry out of balance all the time. 10% is a good guide.

 

[NS Mike D]

Red Sea publishes target numbers for different types of tanks (ultra low, mixed reef etc). So the first question is do you have target numbers for NO3 and PO4 and how is your tank in relation to that?

Since NOPOX (and other forms of carbon dosing) can reduce NO3 faster than PO4, it's common that your target numbers can get out of balance. While no one knows for sure what causes cyano from coming out of suspension and forming mats, we are fairly certain that the presence of PO4 with the absence or low levels of NO3 is likely to precipitate cyano and put other nuisance algae/bacteria at an advantage over your corals as some of them are able to get N from other sources and thus out compete with your corals.


All that being said, GFO will lock up PO4 and bring it in balance with NO3. Given you NO3 is at 3ppm, I would guess you have sufficient PO4 to be used with NO3 to be consumed by your corals (and macro algae of you use that as part of your biological filtration) and that would continue to take down NO3 and PO4 with it. But given that 0.54 very high PO4 by most published targets be prepared to use GFO to bring your levels to your desired range.

Keep testing and stay on top of this until you get to an equilibrium in your target range (you may also considered reducing carbon dosing since I gather you are close to a desired level of NO3 if your not seeking ULN)

And +1 on those who advise on going slow with GFO as it can wipe out PO4 too quickly

 

[Braves Fan]

The target number in my tank for Phosphates is 0.07 ,, I test my tank water a lot ,, after my Bi weekly water change ,, Phosphates were at 0.06 ,, a bit over a week ,, Phosphates went to 0.07 ,, then 0.08 ,, then to 0. 09 ,, yesterday it hit 0.10 ,,, turned the GFO reactor on for two hours ,, tested again ,, back to 0.07 ,,, turned the reactor off ,, if you leave the reactor run all night and check your numbers in the morning ,, you will be at 0 .. that opens the door to other problems ,,, I turn my GFO reactor on once a day ,, just to put fresh water in the reactor ,, then shut it back off ,, not sure this is a good idea or not ,, buts its what I do ,,

Testing is a big part of this hobby ,, testing is a pain ,, the more you test ,, the more you will learn your tank ,, I would test everyday till you get your numbers back inline ,,

 

[Bossman]

Thanks for your help guys! I test weekly, water changes bi weekly. Normally around 20% for WC. I could reduce that to 10%. The 50% WC was in an effort to reduce the P04 quickly.

The easy corals I've been keeping have not exhausted my Calc and mag. I use RS coral pro and water changes have been enough.

I'll start the GFO and continue to monitor P04.

 

[Braves Fan]

I keep a log also ,,, every time I test ,, I write it down ,, Nitrates ,, Phosphates ,, Mag. ,, Calcium and Alk. I don't test Mag and Nitrates every time I test ,, but I test a lot ,,, keeping a log helps ,, you need to do this ,, test right before your water changes ,, and again after the new water has had time to mix with the tank water ,, test again every other day after that

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for your help guys! I test weekly, water changes bi weekly. Normally around 20% for WC. I could reduce that to 10%. The 50% WC was in an effort to reduce the P04 quickly.

The easy corals I've been keeping have not exhausted my Calc and mag. I use RS coral pro and water changes have been enough.

I'll start the GFO and continue to monitor P04.

in general, while water changes are useful to lower nitrate, they are far less useful to lower phosphate because the majority of phosphate in most tanks is temporarily bound to rock and sand. If you drop phosphate with a water change, that shifts the balance and more comes off the rock, almost but not quite back where it started.

 

[Bossman]

in general, while water changes are useful to lower nitrate, they are far less useful to lower phosphate because the majority of phosphate in most tanks is temporarily bound to rock and sand. If you drop phosphate with a water change, that shifts the balance and more comes off the rock, almost but not quite back where it started.

Very interesting, I assumed it would lower the phosphate. I've used WC to lower nitrates in the past before I started dosing.

What I did yesterday was manually clean the tank, scrub the rocks, tanks walls, scoop as much red cyano out of the gravel as I could. I used a net to catch as much material in the water column as possible. Then I did my water change and changed the filter socks twice. The tank looks very good this morning but still signs of some red on the gravel.

After reading your post, I thought I would retest P04. Now the reading on my Hanna ULR is .72! I've used it to test my other tanks this morning and have no reason to doubt it.

I will be adding BRS HC GFO this morning and monitor the tank. The tank is approximately 10 months old. Very few corals to upset at this point.

Thanks you Randy!

 

[Quietman]

In the second half of that...run NoPoX, had PO4 increase after getting NO3 down where I wanted, now I'm running some Phosguard to see what it takes to get PO4 where I'd like. Adding 1 tbsp at a time (up to 3 in my system) just to gently bring them down. So far it's hit and miss, doesn't seem to last long, but that could be as stated with rocks releasing bound PO4 or exhausting removal media (again adding small amounts).

 

[Undertaker]

I use gfo and I only use 3 table spoons on my reefer 350 . It keeps my phosphates at around .05 ( with heavy feeding) took me awhile to find my sweet spot using it. Using to much will bring you to undetectable phosphate. So be careful! I use brs’s regular one, and change it out when my po4 raise. I find my tank is much happier with .05 po4.

 

[Bossman]

I use gfo and I only use 3 table spoons on my reefer 350 . It keeps my phosphates at around .05 ( with heavy feeding) took me awhile to find my sweet spot using it. Using to much will bring you to undetectable phosphate. So be careful! I use brs’s regular one, and change it out when my po4 raise. I find my tank is much happier with .05 po4.

I noticed when I started dosing Nopox, at first the change was very slow and I had to adjust higher and higher until the N03 started to drop. Now all of a sudden I'm where I want to be but need to find that perfect dose to keep it there. Red Sea suggests cutting what you needed to drop the nitrates initially in half. The GFO sounds like it will be a similar experience. I will monitor closely

Thanks for your help and suggestions everyone!

 

[Mathman]

in general, while water changes are useful to lower nitrate, they are far less useful to lower phosphate because the majority of phosphate in most tanks is temporarily bound to rock and sand. If you drop phosphate with a water change, that shifts the balance and more comes off the rock, almost but not quite back where it started.

 

[Mathman]

So how do you absorb all of the phosphate bound to the rock and sand?

 

[Randy Holmes-Farley Verified Community Expert]

So how do you absorb all of the phosphate bound to the rock and sand?

You don’t want to remove all of it because then the amount left in the water would be too low, but to lower it, ongoing consumption by organisms, lanthanum, GFO, etc, can do it.