High Phosphates - Let's lower it!

[Daniel91]

Well, I was testing tonight and found my phosphates at 0.16 using the Hanna ULR ppm checker for both my tanks.

 

Threw me off a little as all the corals are doing great and I did a 20% water change of both tanks (13gal and 10gal) a couple of days ago.

My RO/DI water shows 0 TDS - carbon/sediment is due for a change but could that really it?

 

I always watch my feeding and I do not stock heavy in either tank - what could be contributing to this number?

 

Seeing as corals are happy, I am not in a rush to lower it but I would like to get it down to the ideal level of around 0.05 ppm.

 

 

[xM3THODx]

Are there any signs of new unwanted algae growth on rock work or glass? It may just be the test result...just try again

 

One possibility is often overlooked and can cause increase in phosphate levels and algae growth is a deceased snail or cleanup crew. Most reefers see an algae bloom and end up buying more snails to combat it, when they're actually adding more bioload. Anyway I'm rambling. 

 

If you're concerned about the number just do another water change because it sounds like you know what and how much nutrients are going in. 

 

Good Luck!

[Daniel91]

12 minutes ago, xM3THODx said:

Are there any signs of new unwanted algae growth on rock work or glass? It may just be the test result...just try again

 

One possibility is often overlooked and can cause increase in phosphate levels and algae growth is a deceased snail or cleanup crew. Most reefers see an algae bloom and end up buying more snails to combat it, when they're actually adding more bioload. Anyway I'm rambling. 

 

If you're concerned about the number just do another water change because it sounds like you know what and how much nutrients are going in. 

 

Good Luck!

I am actually not seeing much more algae than usual. I’ll try to do another waterchange but I still got to find the source 

[seabass]

As long as you don't have unwanted algae, then the actual number isn't as important.  But I'd probably try lowering it a little too.

 

9 hours ago, Daniel91 said:

I always watch my feeding and I do not stock heavy in either tank - what could be contributing to this number?

All food, whether eaten or not, contributes to phosphate.

 

Organics contain phosphate.  Once they are broken down, they are released.  And it's not uncommon to have a sand bed become a nutrient sink.

 

Another possibility, phosphate can bind to the surface of rock and sand.  Eventually, this is leached back into the water.

 

I like partial water changes to deal with nutrient issues, but sometimes additional help can be required.  A media like Phosguard can be used (along with testing) to reduce phosphate levels.  Be careful, as chemical media has the potential to lower levels too quickly and/or too low.  One of the reasons your corals are doing well, is the presence of phosphate.

[Clown79]

I've had mine higher and no algae. I did lower it with phosguard and larger waterchanges to about your levels. 

 

 

I still have no algae issues.

 

If you aren't having any issues, I wouldn't do any drastic changes. Start with slowly lowering it.

[FlytheWMark]

36 minutes ago, Clown79 said:

I've had mine higher and no algae. I did lower it with phosguard and larger waterchanges to about your levels. 

 

 

I still have no algae issues.

 

If you aren't having any issues, I wouldn't do any drastic changes. Start with slowly lowering it.

Agree with @clown79 .  I got freaked out when I started testing phosphates and they were over 0.25.  I wasn't having algae issues but I "chased the number".  So I used phosguard (too aggressively) and stripped a lot out of my system.  I still use phosguard occasionally if it gets over 0.25 but only in tiny amounts to try to get it to where you are at (0.1).  I've had no issues between these levels so I leave it.  If you aren't having problems, just watch it at those levels.

[Daniel91]

Thanks for the feedback all.

Again, it’s not critical as everything seems happy and I don’t want to chase a lower number - I just want to slowly decrease it.

 

I’ll do an extra waterchange this week 🙂

 

Thanks!

[pokerdobe]

My PO4 levels are .23 as of last night according to the hanna ulr. Everything besides the pearlberry looks decent. 

 

*Shrug. 

[mcarroll]

39 minutes ago, Daniel91 said:

Again, it’s not critical as everything seems happy and I don’t want to chase a lower number - I just want to slowly decrease it.

I would be more confident in the do-nothing approach since that's clearly what the tank is telling you.  (Going off your description, obviously.  Could be you know other reasons that might make a water change make a little more sense to you than me.)

 

The happier the tank looks the less interventions you should make.  Instead you should be establishing as many norms as you can....what's the normal amount of maintenance, food, etc that generated this happy situation?  Keep doing that. 🙂

 

You also didn't mention why this number was a surprise to you.   How often do you test?  How long has the number been "this high"?  Could be that it's "more normal" than you think if you just started testing phosphates or if you don't test often.  

 

On the other hand if you test every week and it went from being .05 for weeks and weeks and suddenly in one week shoots to 0.15, then you have a small mystery.  Still nothing to worry about though...phosphates are good for the tank.  But you do have some questions that could be answered, such as: can I repeat the test and get the same high result?  How about three times?  Did something change in the last week?  Count your CUC.  Count your fish.  Etc.

 

Large nutrient spikes are probably worth some effort to clean up....for example you dump a whole months worth of something/food in the tank by accident.  Whatever the test results, you would confidently deploy as many water changes and GFO exchanges as needed to get things back to normal.

 

If you just have "high phosphates" though, that's not the same as a spike...and as several others have already noted, if that's all it is then it's not something to worry about.  "If it ain't broke, don't fix it."

 

Our problem is that we can't tell as well as you can what generated the numbers....so we can't really say whether you're having a spike you should take action against or whether you just have "high numbers" and you should just sit back and watch corals grow.  🙂 

 

 

[Daniel91]

42 minutes ago, mcarroll said:

I would be more confident in the do-nothing approach since that's clearly what the tank is telling you.  (Going off your description, obviously.  Could be you know other reasons that might make a water change make a little more sense to you than me.)

 

The happier the tank looks the less interventions you should make.  Instead you should be establishing as many norms as you can....what's the normal amount of maintenance, food, etc that generated this happy situation?  Keep doing that. 🙂

 

You also didn't mention why this number was a surprise to you.   How often do you test?  How long has the number been "this high"?  Could be that it's "more normal" than you think if you just started testing phosphates or if you don't test often.  

 

On the other hand if you test every week and it went from being .05 for weeks and weeks and suddenly in one week shoots to 0.15, then you have a small mystery.  Still nothing to worry about though...phosphates are good for the tank.  But you do have some questions that could be answered, such as: can I repeat the test and get the same high result?  How about three times?  Did something change in the last week?  Count your CUC.  Count your fish.  Etc.

 

Large nutrient spikes are probably worth some effort to clean up....for example you dump a whole months worth of something/food in the tank by accident.  Whatever the test results, you would confidently deploy as many water changes and GFO exchanges as needed to get things back to normal.

 

If you just have "high phosphates" though, that's not the same as a spike...and as several others have already noted, if that's all it is then it's not something to worry about.  "If it ain't broke, don't fix it."

 

Our problem is that we can't tell as well as you can what generated the numbers....so we can't really say whether you're having a spike you should take action against or whether you just have "high numbers" and you should just sit back and watch corals grow.  🙂 

 

 

Good points - just to address some of your questions;

 

It was a surprise because the last time I tested ~3 weeks ago it was almost half. I have done nothing different since.

I should be testing PO4 more often but I was waiting for reagents.

I don’t mind phosphates being where they are at as long as I can keep it staple - I am just curious what lead to the increase since the last test.

I’ll test again tomorrow to validate.

[Clown79]

I'm starting to think nitrates play more a role in algae issues than phosphate.

 

Both my tanks are high phos and I barely have to scrape the glass weekly.

 

When my nitrates are 10+, then I get algae.

 

I had more algae issues with higher nitrates and 0 phos than with high phos.

[Daniel91]

Seems to be the same with me for both tanks. “High” phos but moderate Nitrate - I can def get by with scraping once a week and I don’t have much unwanted algae 

[FlytheWMark]

2 hours ago, Clown79 said:

I'm starting to think nitrates play more a role in algae issues than phosphate.

 

Both my tanks are high phos and I barely have to scrape the glass weekly.

 

When my nitrates are 10+, then I get algae.

 

I had more algae issues with higher nitrates and 0 phos than with high phos.

Ditto... glad its not just me thinking this!!

[mcarroll]

0 phos throws the competitive edge to things like green algae that can "mine" phos from aragonite and detritus.

 

Meanwhile everything that is dependent on dissolved phosphate (eg coral) suffers.

 

I think they're all pretty adept at ammonium uptake, so if you have fish then your tank has a steady N source...it may never register as nitrate though.

 

Keeping P available is important....N is too. 🙂 

[MrObscura]

Above 0.1 can possibly slow growth of stony corals , but at your levels and based on how the tanks doing I wouldn't worry about it. You can slowly get it below 0.1 and youre good. 

[mcarroll]

1 hour ago, MrObscura said:

Above 0.1 can possibly slow growth of stony corals , but at your levels and based on how the tanks doing I wouldn't worry about it. You can slowly get it below 0.1 and youre good. 

I think that is turning out to be another one of those low-nutrient worries that doesn't (*ahem*) hold water under scrutiny.

 

It seems like the only thing that matters with phosphate is that there is a consistently available minimum supply....how much above that minimum seems not so crucial.

 

For example, I found this 2013 article a few years ago...it addresses most of the common (mis)conceptions:

The response of the scleractinian coral Turbinaria reniformis to thermal stress depends on the nitrogen status of the coral holobiont

 

There's another related article that I mention in the above blog post that's also worth looking at:

Tissue and skeletal changes in the scleractinian coral Stylophora pistillata Esper 1797 under phosphate enrichment 

 

I think another aspect of thought on phosphate limiting coral growth has been anchored to the factoid about phosphate "poisoning" the aragonite crystal as it's formed.

 

However true "phosphate poisoning" is for lab-grown aragonite, it's apparently untrue (or maybe just irrelevant) for corals, where skeleton secretion is biologically controlled (similarly to some trees and plants) and not simply via precipitation from the surrounding water:

Biological control of aragonite formation in stony corals

 

Click through to read the whole source article on all three links.

[seabass]

I remember this 2011 study discussing phosphate and SPS growth rates:

https://reefbuilders.com/2011/12/05/acropora-phosphate-growth/