View Full Version : Phosphate Limiting, Nitrate Climbing

10/26/2006, 05:27 AM
I've been plagued by high nitrates for a while. They were up around 80 to 120+ until I added some caulerpa. This got them down to 20 to 30 or so. Not bad. Also reduced feeding too.

Lately, my phosphate has been shooting up (maybe from feeding, but fish were losing weight). I use RO/DI Water. At its worst it was 0.5ppm. At that point, I had a FOWGHA :lol: tank. I bought a phosban reactor about two weeks ago and I brought it down to 0.04 for a while and I noticed that the GHA slowed, but its still not gone. I replaced the media yesterday with about 150% of what I had before. I had started about 25% of a 250ml container of Rowaphos and now I've got about half the container in, so 125ml of it. I changed it out when I noticed the phosphate rising again.

Lately my nitrates have been rising. They're getting up to about 40ppm. My caulerpa isn't growing much either. I'm concernd about limiting their growth due to a lack of phosphate. Is this the cause?

I had harvested about 1/3 of it about a month ago to see if it would promote growth, but it hasn't. It's lit 24/7 by the way.

Tank is 120G FOWLR.

What to do?


Randy Holmes-Farley
10/26/2006, 05:56 AM
Macroalgae and GFO are both good ways to reduce phosphate. But combining macroalgae growth with very aggressive GFO use can lead to problems,not the least of which is slowing or stopping the macroalgae growth and so leaving behind a lot of nitrate.

Are you dosing any iron for the caulerpa? If not, I'd try that:

First Iron Article: Macroalgae and Dosing Recommendations

Second Iron Article: Iron: A Look at Organisms Other than Macroalgae

How much macroalgae do you have? How is it lit?

10/26/2006, 08:55 AM
Hi Randy,
Thanks for replying! I guess I'm getting to the problems that you refer to. :( What else is problematic? Do you think I should only run the GFO (what's that actually stand for anyhow?) for a few hours/day to let the phosphate creep up some?

I'm not dosing Iron, but I've thought of trying that. I'm trying to hunt down some locally.

I've also considered running a RDSB, but I need a good cheap source of sand and a good container. Silica sand I have has little black specs in it that scare me. LOTS of rinsing required, I guess.

I'm not sure how to measure the macro, it's in the fuge which is in almost a cubic foot of water and its pretty loose. Definately have had more. Like I mentioned, I'd cut back some of it recently to see if it'd promote growth, but it hasn't grown much. Should I try another species?

Planning a 30Gal water change this Sat or Sun.

Randy Holmes-Farley
10/26/2006, 09:20 AM
If you drive down nutrients too far, you can actually kill the macroalgae. I had that happen when I experiments with adding more limewater and vinegar. I think the bacterial growth used up nutrients, then much of the the macroalgae couldn't get enough and died. That then makes it hard to stop the vinegar without nutrients rising again.

I'd let the macroalgae pack the available space until it seems so crowded that it cannot get light to anything except the surface layer, then thin it a bit. But in general, it is good to have as much as possible to try to outcompete the hair algae.

Seachem Flourish Iron or Kent's iron are good iron supplements.

10/26/2006, 09:59 AM
Pack it in there, 'eh? Maybe I'll see if I can't get ahold of some more while I'm at it. I'll reduce the phoshate removal and research and add some iron too.

Thanks for your help

Randy Holmes-Farley
10/26/2006, 11:07 AM
Sounds good.

Good luck. :)

10/31/2006, 04:39 AM
Had some difficulties finding the iron locally. Probably could have ordered something and it been here by now, but the LFS will have Kent's in on Thursday. In the mean time I used some of the Kent's Nano Reef Part A (I think--the one that has the iron and other trace elements). It was the best I could find for the time being. It doesn't have enough iron though and I can't really check all of the elements so only did one dose.

Nitrates are pretty high. Did a 25% water change. They came down a little bit. Phosphate is pretty low still. Shut off the phosban reactor. Any harm in letting it sit connected to the tank and just no flow through it? I've been feeding a little heavier and adding the frozen food liquid to the tank (to boost the phosphate). I also picked up some Chaeto (had Caulurpa before) to add to the fuge since my macroalgae was looking a little funky and hadn't grown much lately (understandable).

I've tried to be extra vigilant with the GHA removal lately and I think its growth might be backing off. Ordered a Maxijet 1200 and an oceanflow mod kit too. Hopefully it'll keep any gunk from settling on any rocks. Should help some.


Randy Holmes-Farley
10/31/2006, 07:06 AM
How low is the phosphate? It would have to be undetectable with most kits to be limiting, IMO.

10/31/2006, 10:59 AM
My Salifert test was less than the first color gradiant--that was .03 if I recall? I forget w/o looking at the card. Then again, I can't read those well if my life depended on it. Second opinion said clear. Will test again tonight though.

10/31/2006, 03:27 PM
New development! http://www.reefcentral.com/forums/showthread.php?s=&threadid=962732 Please advise, Randy.


Randy Holmes-Farley
11/01/2006, 05:59 AM
Bacteria don't bloom from low pH. Bacterial blooms caused by organics will themselves lower pH as the bacteria convert the organics into CO2, so that may be what they are noticing, but unless you added a lot of organics, it may not be a bacterial bloom.

Cloudiness can be a chemical precipitate (often a limewater overdose) a spawning event (macroalgae, corals, etc) or a bacterial bloom.

Is it still cloudy?

11/01/2006, 10:34 AM
Hi Randy,
Thanks for the reply. I considered a parcipitation event, but ruled that out from the low pH. Maybe macro going sexual, but it's too white and I thought that should be green or brownish. It's lit 24/7 though, and I actually threw more light on it last night in case it'll up the O2.

LFS thought some die off from lowering the pH, but I don't know. I can't think of any other reason, unless something may have gotten in there that I don't know about. Actually....there could be a very very slight chance the a little piece of blue cheese could have gotten in there. What would that do? Long story short, don't shake with the lid off when your tank is in the dining room.

We shut the light off early at about 5:30P last night and it didn't come on until 9 this morning, and the girlfriend said that it looked much better this morning, but it isn't entirely gone. The lunch time update was that its unchanged from this morning


Randy Holmes-Farley
11/01/2006, 12:40 PM
I doubt a tiny piece of cheese would do anything special. What species of macroalgae do you have? How do they look?

11/01/2006, 01:14 PM
Hmm...thought cheese might have some harmful bacteria maybe on it. Ya, dunno what else coulda gotten in there.

I have some caulurpa that looks (and has been for a few of weeks) kind of raggaty. It's light green. That's what I had posted about originally when nitrate up, phosphate down. I've had this clump for about 10months and harvested 2-3 times.

I added about 5.5oz (IIRC), by weight, of chaeto on Monday. It's bright green. Water was clear then.


Randy Holmes-Farley
11/01/2006, 01:28 PM
If the Caulerpa turns suddenly white, that might be the result of a macroalgae sporulation event.

I'm not sure what your issue is.

11/01/2006, 02:31 PM
Yup. I've got issues :( I'll check it closer. Thanks for all your help.

Randy Holmes-Farley
11/02/2006, 04:33 AM
You're welcome. :)

Let us know what happens and if you figure out what it was.

11/02/2006, 04:38 AM
Wellllll.... tank was clear last night. I'm going to attribute it to a bacterial bloom because my ammonia was zip, as was phosphate, and nitrite. Nitrate was signifigantly lower. All is well, so it seems. Thanks again, Randy!


Randy Holmes-Farley
11/02/2006, 09:00 AM
Good to hear!

Happy Reefing. :)