is phosphate level swings a problem in reef?

zheka757

New member
I'm just curios about my phosphate levels, im currently using gfo to try to keep my phosphates down, usualy they are around .20-.30 using gfo it drops down to .05-.08 over 24 hours. if i let it go over 2 weeks it will be back up in .15 range. im still learning my system to keep my phosphates under control, but im just worried about my sps- acros as far as not stressing them out by this phosphate deal. so my question is is dropping that much (from .15 to .07 in 24 hours) consider a stress to corals?
 

thegrun

Team RC
I doubt a one time drop would harm anything, but I would consider changing out the GFO more frequently than once every two weeks if you are seeing consistent drops and rises in phosphates from 0.05 back up to 0.15. Long term I think the corals would not fare well with those kinds of fluctuations. Try changing it out once a week for a few weeks to see if you can pull out the built up phosphates and keep the fluctuations somewhere in the 0.0 to 0.10 range.
 

Timfish

Timfish
Premium Member
Up welling on reefs will expose corals to sudden changes in phosphates. While generally most corals prefer PO4 (inorganic dissolved phosphate, orhtophosphate) many corals may also use Particulate Organic Phosphorus (POP) and Dissolved Organic Phosphorus (DOP), niether of those we can test for. As long as you keep your PO4 above the .03 mg/l identified by researchers at Southampton University in England your corals should be ok. Since phsohprus is supplied by feeding and consumed by corals (and everything else living) the dips in your fluctuations might reflect either disruptions in feeding or quick growth in something in your system. If you search my name and the terms "Phosphorus" "PO4" I have posts with links to a lot of the research done by scientists on phosphorus and corals.
 

zheka757

New member
i honestly don't know where is my phosphates coming from in in such a rapid increase, i tried to decrease foods before, cancel frozen foods, no help. keeping gfo have surely helped, my acropora have finally started growing. right now its being over a week where my phosphate has being in same range is in .06-.08 and nitrates always being in 2.0ppm but also i start doing weekly 50 gallon water changed with instant ocean salt, Prior to this i was doing Reef Chrystal's every 50gallon/10 days water changes.
 

Timfish

Timfish
Premium Member
Biofilms and sponges are all playing with phosphorus as well as everything else living. Corals can use enzymes to convert some forms of DOP into DIP, it seems reasonalble to me some of the other stuff in systems may bea ble ot do it also. This is a good example supporting the addage "dont's chase numbers". We can't test for many of the forms of phophorus and nuitrogen. We can't even monitor the processes that are using the forms we can test for. AS long as PO4 stayed above .03 mg/l threshold identified by Southampton university I'd be happy.

Forest Rohwer "Coral Reefs in the Microbial Seas"
https://www.youtube.com/watch?v=-R2BMEfQGjU

Changing Seas - Mysterious Microbes
https://www.youtube.com/watch?v=c7hsp0dENEA

Nitrogen cycling in hte coral holobiont
https://youtu.be/DWItFGRQJL4

Richard Ross What's up with phosphate"
https://youtu.be/ZRIKW-9d2xI
 

Michael Hoaster

Registered Seaweedist
Premium Member
I'm by no means an expert on this, but it does seem strange that your phosphate comes back so quickly. It may point to your water source or your rocks. I've heard city water can contain phosphate. Did you scape with dry rock? I've heard that can leach phosphate for quite awhile. It's something to look into. Replacing GFO weekly sounds expensive. I'd be curious to hear if you figure out the source.
 

zheka757

New member
I'm by no means an expert on this, but it does seem strange that your phosphate comes back so quickly. It may point to your water source or your rocks. I've heard city water can contain phosphate. Did you scape with dry rock? I've heard that can leach phosphate for quite awhile. It's something to look into. Replacing GFO weekly sounds expensive. I'd be curious to hear if you figure out the source.
I'm very curious my self as well. I have tested my rodi water, and that shows nothing on my hanna checker. The tank is coming up on 3 years that I have started with cured pukani dry rock, I dont know what is the source of my phosfates, but I'm currently coming up on 3 weeks with keeping it under control, with different salt, and weekly water changes. Also gfo media have not being changed in 2 weeks and last time I checked the levels where still under .09
I'm only chasing my phosphate numbers because I had acro frags that have not being happy in my tank for so long, and as soon as used first time gfo, I knoticed polyps started to come up, and now I got good growth in my acro's, I mean coincidence or not, im just happy something if finally working for me with acro's
 
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Michael Hoaster

Registered Seaweedist
Premium Member
Three years seems likely long enough for your dry rock to leech out. I haven't heard of any salt mixes being high in phosphates. Word would get out quickly and they'd be out of business, I would think. Weekly water changes is a lot in my book, but I go months, with a heavily planted tank.

I wonder if a slow growing macro algae could help your situation. Since your nutrient levels are generally low, a fast growing macro like chaeto, caulerpa or ulva wouldn't work. But a slower growing plant like gracilaria can do fine in less nutrients. Either in a refugium or right in the display, Gracilaria might do the trick. It doesn't require a ton of light either, so it's pretty flexible, location-wise. Herbivore fish like tangs would eat it, so if you have those, a fuge might be your only option. It's a thought.
 

zheka757

New member
Three years seems likely long enough for your dry rock to leech out. I haven't heard of any salt mixes being high in phosphates. Word would get out quickly and they'd be out of business, I would think. Weekly water changes is a lot in my book, but I go months, with a heavily planted tank.

I wonder if a slow growing macro algae could help your situation. Since your nutrient levels are generally low, a fast growing macro like chaeto, caulerpa or ulva wouldn't work. But a slower growing plant like gracilaria can do fine in less nutrients. Either in a refugium or right in the display, Gracilaria might do the trick. It doesn't require a ton of light either, so it's pretty flexible, location-wise. Herbivore fish like tangs would eat it, so if you have those, a fuge might be your only option. It's a thought.
Yes, I do have a somewhat refugium, I forgot what they called but my tang do love it when I feed them with it. I also have about 50+ mangrove "blooming" in my sump with lights on for abou 16 hours from evening to morning. This was actually my goal to keep running gfo until my refugium will kick in and take over my phosfates,
 
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