No drop in phosphates after 40% water change

[john.m.cole3]

tank is 2 weeks old post cycling.

I changed 40% of my water yesterday. 32 gallons out of an 80 gallon system.
Nitrate was between 25 and 50 (Salifert) and phosphate read 38 ppm/ .1165 (Hanna ULRS)

I mixed my water in a 32 gallon Brute using regular IO salt. This is the 3rd use of this trash can that I bought new just for this purpose.

After the change, my nitrates dropped to 25 or maybe slightly less, but my phosphates read 37 ppm. Okay it dropped by 1 ppm, but that's not the 40% reduction I was hoping for.

I have 2 more large water changes planned over the next 2 weeks to reduce my nitrates to around 10. I was going to wait to put my reactor online until then hoping the large WC would get these 2 parameters closer to ideal for me.

I am shooting for nitrates 2-5, and phosphates between .02-.04.

Has this happened to anyone else?
Any ideas of how to move forward from here?

 

[Randy Holmes-Farley Verified Community Expert]

Water changes do not drop phosphate as much as one expects because there's a large reservoir attached to the rock and sand. That comas back off when you try to drop the levels.

For that reason, water changes are not a good way to reduce phosphate.

If you keep at it with other export methods, such as growing macroalgae or ATS, GFO, aluminum oxide, or lanthanum, you'll eventually be able to bring it down.

 

[john.m.cole3]

Time to fire up my reactor!

How much of regular BRS GFO should I use in their single reactor to drop my PO4 ASAP?

In my old 46 gal I would combine 1 cup rox GAC and 1/2 cup GFO and change monthly to maintain my PO4 at .03 (not sure if that bit of info is helpful)

 

[bobman]

If it were me I would run 1.5 cups of GFO and adjust if needed and get a separate reactor for GAC. The GAC is really only effective for about a week after that it is not very useful

 

[john.m.cole3]

If it were me I would run 1.5 cups of GFO and adjust if needed and get a separate reactor for GAC. The GAC is really only effective for about a week after that it is not very useful

Thank You! I was under the impression that it lasted longer...

 

[bobman]

It does somewhat but the vast majority of it gets used up very quickly as the pores get clogged up. Ideally it depends on the carbon you run but honestly you don't really need to run carbon 24/7 in the reef tank. Only when your water seems to get a little yellow then toos the carbon reactor on there for about a week it will be cleared up.

 

[Randy Holmes-Farley Verified Community Expert]

Thank You! I was under the impression that it lasted longer...

The lifetime of GFO depends on two factors: the levels of things that bind to it and occupy binding sites (phosphate, silicate, organics, etc) and on the GFOparticlesw getting covered with generalized crud, which can include bacteria, calcium carbonate preciptitae, etc.

High phosphate can deplete GFO in a few hours by the first mechanism. Even with no phosphate, the latter effects likely kill it within a month or less.

 

[jduck]

Have you tested the newly mixed water?

 

[MikeyAl]

Water changes do not drop phosphate as much as one expects because there's a large reservoir attached to the rock and sand. That comas back off when you try to drop the levels.

For that reason, water changes are not a good way to reduce phosphate.

If you keep at it with other export methods, such as growing macroalgae or ATS, GFO, aluminum oxide, or lanthanum, you'll eventually be able to bring it down.

A simple DIY ATS worked for me.

 

[MikeyAl]

I ran the ATS for awhile and my problems seemed to go away. I had some issues with it and started running gfo since I had the reactor. All is good. Listen to Randy.

 

[john.m.cole3]

A simple DIY ATS worked for me.

I've wanted to try of these for a while, but don't know where I'm my sump I would put it

 

[MikeyAl]

I've wanted to try of these for a while, but don't know where I'm my sump I would put it

Send a pic of your sump

 

[MikeyAl]

Water changes do not drop phosphate as much as one expects because there's a large reservoir attached to the rock and sand. That comas back off when you try to drop the levels.

For that reason, water changes are not a good way to reduce phosphate.

If you keep at it with other export methods, such as growing macroalgae or ATS, GFO, aluminum oxide, or lanthanum, you'll eventually be able to bring it down.

Randy. I've heard of people using agent green lanthanum chloride. They use it on the show Tanked. What is the downside? I am not a big fan of adding more chems unnecessarily

 

[Randy Holmes-Farley Verified Community Expert]

There are a few potential downsides, but lanthanum is an OK method.

I discuss it here:

Phosphate In The Reef Aquarium
https://www.reef2reef.com/blog/?p=3184

from it:

Soluble Metals to Bind Phosphate

There are several approaches that add soluble metals to bind and precipitate phosphate. The most popular involves adding lanthanum, which precipitates as lanthanum phosphate and/or lanthanum carbonate (which itself may contain some lanthanum phosphate). The lanthanum approach is widely used in the pool industry to reduce phosphate, and seems to often work well in aquaria. It is also very inexpensive, using products such as Seaklear (make sure it is a pure lanthanum version as mixtures with other metals also exist). Note that this method reduces alkalinity, as removing carbonate and phosphate as a lanthanum precipitate will reduce alkalinity.

One way to use it is to drip is slowly just upstream of a particulate filter to catch and remove a substantial amount of the precipitate that is formed. One drawback to the lanthanum approach is that much of the precipitated material may escape capture and simply settle out in the system somewhere. That may not be an issue, but many aquarists do not prefer to accumulate such material. A second concern is that some people have observed problematic reactions from aquarium inhabitants. While there are not a lot of such stories, it is enough for many aquarists to look for other options.

However, due to its low cost, this approach is especially well suited to outside of the tank operations, such as the removal of excess phosphate from phosphate-contaminated calcium carbonate rock that is later to be added to a reef aquarium.

Soluble iron has also been used in this way, but not nearly so often as lanthanum.

 

[MikeyAl]

Thank you!

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing.

 

[smiley28]

Check @melev for a description and use of lanthanum chloride. He posted up a video about it awhile back where he uses it by dosing it into his skimmer.

http://reef2reef.com/threads/tired-of-phosphates.129798/