I have used with no complaints, its not as long lasting as gfo. Go lightly with it at first see how much you need, as well test often when you find that to gauge a replacement schedule. I replaced with my carbon put both in the same reactor.
I use a BRS dual reactor, carbon in one side, Phosguard in the other. I like it. As the other poster mentioned, start with a small amount—test your phosphate levels— and use increasingly more if you need to. It might need to be changed out more frequently than some others forms of media, but it’s cheap given how little you will likely use.
I was about to start a thread, but this one is going.
So I have a similar situation. I have 110 Gallon tank with 50 Gallon Sump so roughly about 150 Gallons of water.
My Phosphate is 0.20-0.25 and my target is to get to 0.1 (or a tiny bit lower)
I actually called Seachem since my experience with Phosgaurd is a bit confusing.
I explained to them that I was using Phosguard in media bags IN SUMP flow areas, and it would bring P down a tiny bit, and stop.
Then I decided to put the Phosgard into a Two Little Fishies reactor. 1 Cup since the instructions say 1/3 Cup per 50 Gallons.
That is how I got my P down down from 0.25 to 0.21 and again things Stalled. After about 4 days.
Seachem explained to me that Phosguard (Aluminum based Remover) is lighter than typical (Iron Based GFO). It reduces phosphate slower than GFO, and exhausts faster than GFO.
That is fine by me since I don't want to drop P too fast, since I have nothing but SPS in my Tank. (QUICK DROPS in P can be deadly to SPS)
It's also fine by me since the price is better than GFO.
However I want to know when it's time to replace Phosguard, and how much of a reduction I can expect.
Normally when I used GFO in my reactor, I would test the Reactor output, and would get P=0.00 When reactor output was no longer 0.00, that would mean GFO is exhausted and time to replace.
This is not the case with Phosguard. My Reactor output is not 0.00 even if fresh, and I would say not much lower than Tank P Level.
That is where Seachem explained I might need to used more than a cup.
Partly due to the fact that Phosphates are being added daily by feeding fish/corals.
Also Seachem explained that Phosguard has a capacity to reduce P by 3 mg/L. I'm not exactly sure what that means.
[mg/L is ppm] but how do you use that number to figure out capacity of Phosguard on 150 Gallons of Water with P=0.25 ppm. (What will P drop on that 1 CUP of Phosguard? Doesn't matter to me how fast, just how much, based on water volume) Know that calculation would help to know how my (P in ppm) can (1 cup) absorb (per volume of water).
Wondering how folks have figured out how to more accurately use Phosguard.
Did some more digging.....
Here is a good article about Phosguard, and some scientific evidence proving Phosguard does NOT release aluminum as suggested by some folks.
It may release some if not used properly (should be rinsed before using, and should not tumble when water flowing thru it).
I've been using it for a few weeks and my SPS have been getting better (many reasons) but no negative impacts using Phosguard.
I would be more worried using GFO since it will drop P fast.
I have 120 gallon system so with the recomended 1 3rd cup per 50 gallons I put 2 3rds cup in. In 5 days it dropped my phosphates from .1 to .07 .I will add another 2 3rds cups and see if it stays at a .03 drop , And repost.