I have half a 4L sitting here going to waste. I used it in my 75G and it began bleaching my toadstool coral. I read a couple articles pointing to the aluminum based Seachem. I stopped using it and the coral recovered for the most part and thats been about 4 weeks now. I used it in my 29G (since I had no sarcophyton in it) and the corals and inverts started looking a little weird. I highly recommend using something else. I am currently testing (Two Little Fishes) Phosban which so far has been a disappointment (Using the phosban 'reactor') I also have RowaPhos on deck to try for a second time since the first time out with it provided little to no results. In the defense of the Phosban I do not think I have enough water flow for it, but I will be hooking to a 90G/Hr pump this weekend...
To fail to plan is to plan to fail.