Phosphates @ 0.3 -- why is this a problem?

[pseudorand]

My phosphates have been at 0.3ppm for as long as I've been measuring (~3 months). Why is that bad? (i.e. What negative effects should I expect to see.) Phosphates did drop to 0.2 measured via Nyos two weeks ago, so I though I was on the right track. But this week they're back up to 0.3. Darn you, Chemistry!

My tank is a 120g reef + 20g sump, up for about 6 months. Plenty of LR, 2 full-grown clarkii clowns, 1 royal gramma, 2 firefish, CUC, 5 or so green zoa/paly frags. I feed 1 cube of frozen / day, alternating between Emerald Entree, Marine Cuisine and Brine Shrimp.

I'm trying to get stable params before adding more corals. I'm able to keep alk at 8.0 with about 1g kalk/week and Mg @ ~1350 with 200g BRS Mg / month. Nitrates have measured 1ppm via Nyos for months. About 2 months ago I added Pom Pom and Chaeto to the sump to help with phosphates. Both have grown like mad, and I'm about to cut them back for the first time with tonight's water change.

I've also been doing 15% weekly water changes for the past month (up from monthly) to try to get phosphates under control, though tonight I learned that water changes won't do much since phosphate binds to rock and substrate. However, does this mean I won't see the measured value change until I've pulled enough out that it stops leeching from the rocks, in which case I should continue with more frequent water changes? Or does it mean that water change won't ever remove phosphates?

The only problems I see other than the measurement itself is diatom growth, but so far it's nothing my urchins and some precision suctioning haven't been able to keep up with.

So how should I proceed? P04 it's 0.3, but a stable 0.3. I have no SPS plans. Should I just go for softies and maybe a few LPS?

What else should I try to get it down? Are there phosphate export methods other than GFO? I think I have a light fish and feeding load. Why is it so high to begin with?

My hypothesis on why it dropped and went back up (other than measurement error) is that my Chaeto was starting to work, but slowed its growth when it filled my sump. I may find out if that's the case after cutting it back, but does that sound possible to anyone else?

 

[X-37B]

First determine what level you want to run.
Then keep it stable.
When I started my 120 11 months ago with 50/50 live and caribsea.
Not much of a cycle. After 1 month no3 1-2 po4 .68.
I added a small amount of phosgaurd to the sump in a mesh bag. Checked po4 daily until it was .06. I then removed it and po4 stays .02-.06 with no3 2-3 for the last 10 months.
I feed 2 cubes or reef freny equivalent amout 3-4 times a day with 11 fish.
I like phosgaurd as its simple to put in and remove without adding another piece of equipment.

 

[MERKEY]

First determine what level you want to run.
Then keep it stable.
When I started my 120 11 months ago with 50/50 live and caribsea.
Not much of a cycle. After 1 month no3 1-2 po4 .68.
I added a small amount of phosgaurd to the sump in a mesh bag. Checked po4 daily until it was .06. I then removed it and po4 stays .02-.06 with no3 2-3 for the last 10 months.
I feed 2 cubes or reef freny equivalent amout 3-4 times a day with 11 fish.
I like phosgaurd as its simple to put in and remove without adding another piece of equipment.

+1

This is basically the approach we took.

 

[Fishingandreefing]

Last week I was at .20 and I am not going to touch it anymore till anything not good

 

[pseudorand]

First determine what level you want to run.
Then keep it stable.
When I started my 120 11 months ago with 50/50 live and caribsea.
Not much of a cycle. After 1 month no3 1-2 po4 .68.
I added a small amount of phosgaurd to the sump in a mesh bag. Checked po4 daily until it was .06. I then removed it and po4 stays .02-.06 with no3 2-3 for the last 10 months.
I feed 2 cubes or reef freny equivalent amout 3-4 times a day with 11 fish.
I like phosgaurd as its simple to put in and remove without adding another piece of equipment.

That sounds easy and is exactly what I wanted to hear. However, I want to understand why. Is the phosguard sucking the PO4 out of the rocks for me? Why won't it just build up again after I remove the phosguard?

As for how it got to 0.3 in the first place, I got rock from two existing tanks, so it may be that those tanks had high PO4 and I just inherited the problem. If that's the case, it makes sense that it wouldn't build up again so long as my feeding schedule doesn't exceed the capacity of my chaeto and other photosynthetics to absorb what I put in.

 

[Spieg]

0.3 is pretty high although it probably wont actually kill anything, it will for sure inhibit coral growth and contribute to algae growth. I try to stay below 0.1 as a rule (0.03-0.04 being ideal). You may be correct about it leaching from your rock and sand but food may be contributing to the level as well. There are a lot of products to lower the level, but as you said, if it is coming our of the rock/sand, it will probably increase again once you stop using whatever product. It will probably take a year or so of treatment before the rock/sand will release enough to stop being an issue. I prefer lanthanum chloride dosed once or twice a week to battle a chronic problem (it's easy and probably the least expensive option).

 

[Nano sapiens]

Phosphate will bind to calcareous substrates (such as live rock, coral sand, shells, etc.). When the water column has a lower level of phosphate than the rock, phosphate will leach from the rock until a new equilibrium is established. Once an equilibrium of (enter arbitrary phosphate ppm number here) is reached, then nutrient input/export will be the major deciding factor determining whether the level goes up or down.

 

[X-37B]

Here is what I have observed. Test po4. Get a turkey baster and blow off the rocks. Retest Po4. It always goes up for me. Moving established rocks and or a sandbed, I run BB, to another system can release po4.

 

[Randy Holmes-Farley]

That sounds easy and is exactly what I wanted to hear. However, I want to understand why. Is the phosguard sucking the PO4 out of the rocks for me? Why won't it just build up again after I remove the phosguard?

It likely will.

 

[pseudorand]

It likely will.

Which is exactly what I would guess.

If water changes and phosguard and cheato won't permanently correct my phosphate issue, what will? Is a GFO reactor my only option?

Or should I dose nitrates / exploit the redfield ratio? I've been reading a few posts on that, but I have yet to find one that makes sense to me. Anyone have a favorite practical guide on the subject?

 

[Randy Holmes-Farley]

Which is exactly what I would guess.

If water changes and phosguard and cheato won't permanently correct my phosphate issue, what will? Is a GFO reactor my only option?

Or should I dose nitrates / exploit the redfield ratio? I've been reading a few posts on that, but I have yet to find one that makes sense to me. Anyone have a favorite practical guide on the subject?

They will correct it, but with ongoing use of an appropriate amount. They are not a use it and be done effort.

i don't think the Redfield ratio has much use for us, except that from the simplistic sense that if one of N and P (and some other things like iron) get too low, organisms may not be able to grow enough to lower the other.

 

[pseudorand]

Thanks for the reply. I think I'll try phosguard and try to remember to post back here about my experience: Can I take it out after initial reduction as 90's reefer reports, or do I have to run it permanently as RHF suggests.

However, I don't have room for a phosphate reactor, and I'm afraid either that or phosguard will pull them too low, risking dinos. If anyone has additional advice on keeping phospates under control, please reply. Or even an explanation for why mine might be persistently high, but steady and/or the theory behind how it should work (i.e. is it more complicated than food in, chaeto + skimmer out)?

 

[MERKEY]

Thanks for the reply. I think I'll try phosguard and try to remember to post back here about my experience: Can I take it out after initial reduction as 90's reefer reports, or do I have to run it permanently as RHF suggests.

However, I don't have room for a phosphate reactor, and I'm afraid either that or phosguard will pull them too low, risking dinos. If anyone has additional advice on keeping phospates under control, please reply. Or even an explanation for why mine might be persistently high, but steady and/or the theory behind how it should work (i.e. is it more complicated than food in, chaeto + skimmer out)?

I am using phosguard as we speak....I have been adding 1 cup per every 4-5 days in a 75g and watching the phos drop around .2 every change.

We started at .8 and we will be doing a fourth round and we are now at .2 after 3 rounds.

Just watch it and take it slow....we are going to take it out when we get to .05 and see how long it takes to start creeping again.

Once it starts creeping we will add 1/4 cup to keep it at .05

Thats the hope haha

 

[Randy Holmes-Farley]

Thanks for the reply. I think I'll try phosguard and try to remember to post back here about my experience: Can I take it out after initial reduction as 90's reefer reports, or do I have to run it permanently as RHF suggests.

However, I don't have room for a phosphate reactor, and I'm afraid either that or phosguard will pull them too low, risking dinos. If anyone has additional advice on keeping phospates under control, please reply. Or even an explanation for why mine might be persistently high, but steady and/or the theory behind how it should work (i.e. is it more complicated than food in, chaeto + skimmer out)?

Maybe it seems like there is uncertainty here, but phosphate dynamics in reef tanks is well understood.

I don't think there is any disagreement of what is needed to get a binder to reduce phosphate. You can drop it with a temporary use, but if your ongoing additions by food still outpace consumption, it will rise again, possibly slowly as more rebinds to rock and sand that you stripped out with the binder initial use. That doesn't mean you should use one, jsut what will happen if you do.

You can always drop phosphate as slowly as you want by using less and less GFO or aluminum oxide (phosguard is one brand of aluminum oxide).

Why is phosphate high? You fed more than the tank organisms incorporated into tissues.

Why is is steady? If it is, then additions are matching consumption, and by "consumption" I am including phosphate binding to rock and sand. At higher phosphate, more binds to rock and sand. Thus, the rock and sand binding strongly tends to stabilize phosphate at whatever level it is. Like a pH buffer stabilizing pH.

0.3 ppm phosphate is not high enough to prevent a great reef tank. Don't get too worked up if it seems hard to "control".

 

[NanJ]

I thought this video put some perspective on chasing numbers and conventional wisdom about nitrates and phosphates.

 

[pseudorand]

Well, about 4 months later my phosphates fluctuate between 0.1 and 0.15 ppm. I've been using 1c phosguard during that time, but I change it when I do a water change, which is about every 1-1.5 weeks rather than the 4 days recommended on the package.

I also fed reefroids to my coral QT recently and phosphate measured significantly darker than the 1ppm where my Nyos test kit tops out. To be fair to reefroids, I probably significantly over-fed. I started using 1/3c phosguard in that 39g tank and changing it at the recommended 4 day interval (as well as stopping the reefroids). Today (about 3 weeks later) phosphate measures < 0.05ppm (which is where I can't tell the difference between the colors on my Nyos kit).

So I'd say phosguard works as advertised. My QT is also bare bottom and has no rocks or other such things to act as phosphate reservoirs. I'm sure this surprises none of the biochemists reading this thread. But I figured a nice persuasive anecdote that agrees with the data can't hurt.