SO. You get GFO in a jar. There's a sock with it, so you could just put it in your water flow---but this only works with real tiny tanks, because most of it is compacted in the sock and about as effective as another rock.
Best deal is a reactor. They come in the 200 gram size and the 750 gram size. The jars of medium are 150 grams. Go figure.
WASH the medium: clams don't like the dust and probably corals don't.
Then install 150 to 200 grams of the medium in the small reactor and as much as you want to run, up to 750 grams, in the large reactor.[\QUOTE]
Flow Is Absolutely Critical For GFO
GFO is a heavy granular solid. Because of the small size of the GFO granuales, water does not flow easily among these granules. All the phosphate absorbing happens at the surface of these granules. If the water is not passing by all the surfaces of all the granules because the GFO sits in the sump as a motionless pile, GFO cannot remove phosphates. Hence the need for a reactor
How Much GFO
If you do not have antibodies to arithmetic, it is simple to figure out how much GFO you need to bring phosphate levels to "0". By measuring the ppm of phophate in the system and having an estimate of the total water volume in the system, calculate the total amount of phosphate in the system
Total milligrams of PO4 in system = gallons in system X 3.7 X ppm
Kilograms of GFO needed = miiligrams of phosphate in system / 2500
GFO absorbs about 2.5 grams of phosphate per kilogram of GFO. And when used in a reactor it will absorb this amount in a couple days. The size of the reactor is not as important as keeping it charged with active GFO as soon as the GFO becomes exhausted. A small reactor will need to be charged more often than a large one and may work a a little more slowly, but it will do the job. So, regular testing is necessary. Weekly phosphate testing is a sufficient when bringing down levels of phosphate.
A word on colorimetric tests. Once the the phosphate levels become small, it will be very difficult to estimate a ppm value for phosphate. This won't matter if your goal is to drive phosphate levels very low. Here's how.
Once the test solution color level becomes paler than the last color sample on the color chart, say 0.03 ppm for the Salifert test, you have to start comparing the color to a blank. This will require you to do a very careful, side by side comparison of the test solution and a sample of aquarium water, preferrably in an identical container with the same volume as the test solution. This is the only way to judge that phosphate levels are ultra low. If you see even a hint of blue, keep using GFO. When the blue color is no longer evident, you can stop adding fresh GFO until the weekly test shows the slightest hint of blue. Ask a friend to help judge the color or mix up the containers and see if you can tell which is the blank and which is the test solution.
[\QUOTE]One miraculous week thereafter, the algae in the tank will hit a sudden scarcity of what they need, and die. it happens quite suddenly, over a matter of days.
Will it hurt your cheato moss in your fuge? Nope. Won't. Dunno what that stuff likes, but it's not going to die.
At the point you're rid of the phosphate, you can pretty well shut down your reactor(s) and put them away against a time of need, or sell them on---with no moving parts, they tend to be pretty indestructible.