<a href=showthread.php?s=&postid=6869505#post6869505 target=_blank>Originally posted</a> by mbbuna
jdieck. what do you have to say about the accounts of people using too much at first and having all kinds of problems with SPS?
I want to clarify that in my opinion it is not the amount of media used what causes the problems but how fast you remove the phosphate from the total tank water volume, this is why it is important to use a reactor were the effluent amount of phosphate free treated water can be limited and controlled.
The natural assumption is that the more media used the faster the phosphate is removed but in a reactor it does not work that way. If you fill up the reactor with media and water but then you close the valve are we removing phosphate from the tank? Only from the water inside the reactor. Once all the phosphate in that water is removed the media just holds removal until more phosphate laden water is added. Assuming full phosphate removal from the water pasing through the reactor, an effluent flow of 10 ml per minute will take twice as long (or two times slower) to remove a given amount of phosphate in the aquarium than a flow of 20 ml/min.
Also besides the speed of removal IMO there seems to have been another contributing factor to the coral problems. Initially there were issues in the way the media was first recommended to be applied. If you remember when the media first hit the market the manufacturers recommended not to rinse the media, this resulted in media fines deposited all over the corals, now the recommendation is to discard the initial water passed trough the reactor at start up until the water starts to clear to prevent the media dust to be carried into the water column. Similarly when using a bag, the recommendation was to have the media loose inside the bag (similar to today's recommendation of fluidized in the reactor), now the recommendation is to hold the media tight inside the bag to prevent erosion by the constant agitation that could create small particles that pass trough the bag.
In addition there seem to have been more problems reported with the use of Rowaphos than the use of Phosban. If you take a look at the charts shown in the document I attached above, Rowa is really very fast acting and can adsorb twice the phosphate for the same water retention time than Phosban at similar phosphate concentrations. By the way it adsorbs twice but also costs twice as much on a dry mass to mass comparison.
By the way I use a large 6" dia reactor in my 330 gal water system volume which I load with a full bucket (1200 gr) of Phosban replaced every six months. Enough to remove about 400 mg of Phosphate at concentrations of around 0.01 ppm.
I estimated that if I do not use the media the phosphate level would reach about 0.3 ppm in that time with my normal feeding and water change schedule. That happens to be about 375 milligrams (0.3 mg/lt x 330 gal x 3.7854 lts/gal).
Last but not least, when using less volume than that required to fully fluidize the media I would recommend shaking the reactor once in a while to prevent compaction and solidification of the media by the precipitation of calcium carbonate.
Hope this info helps to clarify the point I am trying to make.
At the end, both methods work, it is just that one seems more practical to me than the other.